mongod.txt

.. _mongod:

==========
``mongod``
==========

.. default-domain:: mongodb

.. contents:: On this page
   :local:
   :backlinks: none
   :depth: 2
   :class: singlecol

Synopsis
--------

:binary:`~bin.mongod` is the primary daemon process for the MongoDB
system. It handles data requests, manages data access, and performs
background management operations.

This document provides a complete overview of all command line options
for :binary:`~bin.mongod`. These command line options are primarily useful
for testing: In common operation, use the :doc:`configuration file
options </reference/configuration-options>` to control the behavior of
your database.

.. seealso:: :ref:`conf-file-command-line-mapping`

.. note::

   .. include:: /includes/fact-tls-1.0.rst

.. |binary| replace:: MongoDB

.. _mongod-options:

Options
-------

.. only:: (not man)

   .. class:: hidden

      .. binary:: mongod

Core Options
~~~~~~~~~~~~

.. program:: mongod

.. option:: --help, -h

   Returns information on the options and use of :program:`mongod`.


.. option:: --version

   Returns the :program:`mongod` release number.


.. option:: --config <filename>, -f <filename>

   Specifies a configuration file for runtime configuration options. The
   configuration file is the preferred method for runtime configuration of
   :program:`mongod`. The options are equivalent to the command-line
   configuration options. See :doc:`/reference/configuration-options` for
   more information.
   
   Ensure the configuration file uses ASCII encoding. The :program:`mongod`
   instance does not support configuration files with non-ASCII encoding,
   including UTF-8.


.. option:: --verbose, -v

   Increases the amount of internal reporting returned on standard output
   or in log files. Increase the verbosity with the ``-v`` form by
   including the option multiple times, (e.g. ``-vvvvv``.)
   


.. option:: --quiet

   Runs :program:`mongod` in a quiet mode that attempts to limit the amount
   of output.

   This option suppresses:
   
   - output from :term:`database commands <database command>`
   
   - replication activity
   
   - connection accepted events
   
   - connection closed events


.. option:: --port <port>

   
   *Default*:
   
   - 27017 if :binary:`~bin.mongod` is not a shard member or a config server member
   - 27018 if :binary:`~bin.mongod` is a :option:`shard member <mongod --shardsvr>`
   - 27019 if :binary:`~bin.mongod` is a :option:`config server member <mongod --configsvr>`
   
   The TCP port on which the MongoDB instance listens for
   client connections.
   


.. option:: --bind_ip <hostnames|ipaddresses|Unix domain socket paths>

   *Default*: localhost

   
   .. note::
   
      Starting in MongoDB 3.6, :program:`mongod` bind to localhost
      by default. See :ref:`3.6-bind-to-localhost`.
   
   The hostnames and/or IP addresses and/or full Unix domain socket
   paths on which :program:`mongod` should listen for client connections. You
   may attach :program:`mongod` to any interface. To bind to multiple
   addresses, enter a list of comma-separated values.
   
   .. example:: ``localhost,/tmp/mongod.sock``
   
   You can specify both IPv4 and IPv6 addresses, or hostnames that
   resolve to an IPv4 or IPv6 address.
   
   .. example:: ``localhost, 2001:0DB8:e132:ba26:0d5c:2774:e7f9:d513``
   
   .. note::
   
      If specifying an IPv6 address *or* a hostname that resolves to an
      IPv6 address to :option:`--bind_ip`, you must start :program:`mongod` with 
      :option:`--ipv6` to enable IPv6 support. Specifying an IPv6 address
      to :option:`--bind_ip` does not enable IPv6 support.
   
   If specifying a 
   `link-local IPv6 address <https://en.wikipedia.org/w/index.php?title=Link-local_address&oldid=880793020#IPv6>`_ 
   (``fe80::/10``), you must append the 
   `zone index <https://en.wikipedia.org/w/index.php?title=IPv6_address&oldid=877601778#Scoped_literal_IPv6_addresses>`_
   to that address (i.e. ``fe80::<address>%<adapter-name>``). 
   
   .. example:: ``localhost,fe80::a00:27ff:fee0:1fcf%enp0s3``
   
   .. include:: /includes/tip-hostnames.rst
   
   .. include:: /includes/warning-bind-ip-security-considerations.rst
   
   For more information about IP Binding, refer to the
   :doc:`/core/security-mongodb-configuration` documentation.

   To bind to all IPv4 addresses, enter ``0.0.0.0``.
   
   To bind to all IPv4 and IPv6 addresses, enter ``::,0.0.0.0``
   or alternatively, use the :setting:`net.bindIpAll` setting.
   
   .. note::
   
      ``--bind_ip`` and ``--bind_ip_all`` are mutually exclusive.
      Specifying both options causes :program:`mongod` to throw an error and
      terminate.


.. option:: --bind_ip_all

   
   .. versionadded:: 3.6
   
   If specified, the :program:`mongod` instance binds to all IPv4
   addresses (i.e. ``0.0.0.0``). If :program:`mongod` starts with
   :option:`--ipv6`, :option:`--bind_ip_all` also binds to all IPv6 addresses
   (i.e. ``::``). 
   
   :program:`mongod` only supports IPv6 if started with :option:`--ipv6`. Specifying
   :option:`--bind_ip_all` alone does not enable IPv6 support.
   
   .. include:: /includes/warning-bind-ip-security-considerations.rst
   
   For more information about IP Binding, refer to the
   :doc:`/core/security-mongodb-configuration` documentation.

   
   Alternatively, you can set the ``--bind_ip`` option to
   ``::,0.0.0.0`` to bind to all IP addresses.
   
   .. note::
   
      ``--bind_ip`` and ``--bind_ip_all`` are mutually exclusive. That
      is, you can specify one or the other, but not both.
   


.. option:: --clusterIpSourceWhitelist <string>

   
   .. versionadded:: 3.6
   
   A list of IP addresses/CIDR (`Classless Inter-Domain Routing
   <https://tools.ietf.org/html/rfc4632>`__) ranges against which the
   :binary:`~bin.mongod` validates authentication requests from other members of
   the replica set and, if part of a sharded cluster, the :binary:`~bin.mongos`
   instances. The :binary:`~bin.mongod` verifies that the originating IP is
   either explicitly in the list or belongs to a CIDR range in the list. If the
   IP address is not present, the server does not authenticate the
   :binary:`~bin.mongod` or :binary:`~bin.mongos`.
   
   :option:`--clusterIpSourceWhitelist` has no effect on a :binary:`~bin.mongod` started without
   :ref:`authentication <authentication>`.

   
   :option:`--clusterIpSourceWhitelist` accepts multiple comma-separated IPv4/6 addresses or Classless
   Inter-Domain Routing (`CIDR <https://tools.ietf.org/html/rfc4632>`_) ranges:
   
   .. code-block:: shell
   
      mongod --clusterIpSourceWhitelist 192.0.2.0/24,127.0.0.1,::1

   
   .. important::
   
      Ensure :option:`--clusterIpSourceWhitelist` includes the IP address *or* CIDR ranges that include the
      IP address of each replica set member or :binary:`~bin.mongos` in the
      deployment to ensure healthy communication between cluster components.


.. option:: --ipv6

   
   Enables IPv6 support. :program:`mongod` disables IPv6 support by default.
   
   Setting :option:`--ipv6` does *not* direct the :program:`mongod` to listen on any
   local IPv6 addresses or interfaces. To configure the :program:`mongod` to
   listen on an IPv6 interface, you must either:
   
   - Configure :option:`--bind_ip` with one or more IPv6 addresses or
     hostnames that resolve to IPv6 addresses, **or**
   - Set :option:`--bind_ip_all` to ``true``.


.. option:: --listenBacklog <number>

   *Default*: Target system ``SOMAXCONN`` constant

   .. versionadded:: 3.6
   
   The maximum number of connections that can exist in the listen
   queue.
   
   .. warning ::
   
      Consult your local system's documentation to understand the
      limitations and configuration requirements before using this
      parameter.
   
   .. important::
   
      To prevent undefined behavior, specify a value for this
      parameter between ``1`` and the local system ``SOMAXCONN``
      constant.
   
   The default value for the ``listenBacklog`` parameter is set at
   compile time to the target system ``SOMAXCONN`` constant.
   ``SOMAXCONN`` is the maximum valid value that is documented for
   the *backlog* parameter to the *listen* system call.
   
   Some systems may interpret ``SOMAXCONN`` symbolically, and others
   numerically. The actual *listen backlog* applied in practice may
   differ from any numeric interpretation of the ``SOMAXCONN`` constant
   or argument to ``--listenBacklog``, and may also be constrained by
   system settings like ``net.core.somaxconn`` on Linux.
   
   Passing a value for the ``listenBacklog`` parameter that exceeds the
   ``SOMAXCONN`` constant for the local system is, by the letter of the
   standards, undefined behavior. Higher values may be silently integer
   truncated, may be ignored, may cause unexpected resource
   consumption, or have other adverse consequences.
   
   On systems with workloads that exhibit connection spikes, for which
   it is empirically known that the local system can honor higher
   values for the *backlog* parameter than the ``SOMAXCONN`` constant,
   setting the ``listenBacklog`` parameter to a higher value may reduce
   operation latency as observed by the client by reducing the number
   of connections which are forced into a backoff state.
   


.. option:: --maxConns <number>

   The maximum number of simultaneous connections that :program:`mongod` will
   accept. This setting has no effect if it is higher than your operating
   system's configured maximum connection tracking threshold.
   
   Do not assign too low of a value to this option, or you will
   encounter errors during normal application operation.

   .. include:: /includes/note-max-conns-max.rst
   


.. option:: --logpath <path>

   Sends all diagnostic logging information to a log file instead of to
   standard output or to the host's :term:`syslog` system. MongoDB creates
   the log file at the path you specify.
   
   By default, MongoDB will move any existing log file rather than overwrite
   it. To instead append to the log file, set the :option:`--logappend` option.
   


.. option:: --syslog

   Sends all logging output to the host's :term:`syslog` system rather
   than to standard output or to a log file. , as with :option:`--logpath`.
   
   The :option:`--syslog` option is not supported on Windows.
   
   .. warning::
   
      The ``syslog`` daemon generates timestamps when it logs a message, not
      when MongoDB issues the message. This can lead to misleading timestamps
      for log entries, especially when the system is under heavy load. We
      recommend using the :option:`--logpath` option for production systems to
      ensure accurate timestamps.


.. option:: --syslogFacility <string>

   *Default*: user

   Specifies the facility level used when logging messages to syslog.
   The value you specify must be supported by your
   operating system's implementation of syslog. To use this option, you
   must  enable the :option:`--syslog` option.


.. option:: --logappend

   Appends new entries to the end of the existing log file when the :program:`mongod`
   instance restarts. Without this option, :binary:`~bin.mongod` will back up the
   existing log and create a new file.


.. option:: --logRotate <string>

   *Default*: rename

   
   .. versionadded:: 3.0.0
   
   Determines the behavior for the :dbcommand:`logRotate` command.
   Specify either ``rename`` or ``reopen``:
   
   - ``rename`` renames the log file.
   
   - ``reopen`` closes and reopens the log file following the typical
     Linux/Unix log rotate behavior. Use ``reopen`` when using the
     Linux/Unix logrotate utility to avoid log loss.
   
     If you specify ``reopen``, you must also use :option:`--logappend`.

   If :doc:`auditing </core/auditing>` is enabled, the
   :dbcommand:`logRotate` command also rotates the audit log according
   to the above parameters. For example, if :option:`--logRotate` is set
   to ``rename``, the audit log will also be renamed.


.. option:: --timeStampFormat <string>

   *Default*: iso8601-local

   The time format for timestamps in log messages. Specify one of the
   following values:
   
   .. list-table::
      :header-rows: 1
      :widths: 20 40
   
      * - Value
   
        - Description
   
      * - ``ctime``
   
        - Displays timestamps as ``Wed Dec 31
          18:17:54.811``.
   
      * - ``iso8601-utc``
   
        - Displays timestamps in Coordinated Universal Time (UTC) in the
          ISO-8601 format. For example, for New York at the start of the
          Epoch: ``1970-01-01T00:00:00.000Z``
   
      * - ``iso8601-local``
   
        - Displays timestamps in local time in the ISO-8601
          format. For example, for New York at the start of the Epoch:
          ``1969-12-31T19:00:00.000-0500``
   


.. COMMENT traceExceptions is internal use only and not in mongod help output

.. option:: --traceExceptions

   For internal diagnostic use only.
   
   .. see SERVER-6667a
   


.. option:: --pidfilepath <path>

   Specifies a file location to store the process ID (PID) of the :program:`mongod`
   process. The user running the ``mongod`` or ``mongos``
   process must be able to write to this path. If the :option:`--pidfilepath` option is not
   specified, the process does not create a PID file. This option is generally
   only useful in combination with the :option:`--fork` option.
   
   .. admonition:: Linux
      :class: note
   
      On Linux, PID file management is generally the responsibility of
      your distro's init system: usually a service file in the ``/etc/init.d``
      directory, or a systemd unit file registered with ``systemctl``. Only
      use the :option:`--pidfilepath` option if you are not using one of these init
      systems. For more information, please see the respective
      :doc:`Installation Guide </installation>` for your operating system.
   
   .. admonition:: macOS
      :class: note
   
      On macOS, PID file management is generally handled by ``brew``. Only use
      the :option:`--pidfilepath` option if you are not using ``brew`` on your macOS system. 
      For more information, please see the respective
      :doc:`Installation Guide </installation>` for your operating system.


.. option:: --keyFile <file>

   Specifies the path to a key file that stores the shared secret
   that MongoDB instances use to authenticate to each other in a
   :term:`sharded cluster` or :term:`replica set`. :option:`--keyFile` implies
   :option:`--auth`. See :ref:`inter-process-auth` for more
   information.


.. option:: --setParameter <options>

   Specifies one of the MongoDB parameters described in
   :doc:`/reference/parameters`. You can specify multiple ``setParameter``
   fields.
   



.. COMMENT clusterAuthMode moved to SSL section

.. option:: --nounixsocket

   Disables listening on the UNIX domain socket. :option:`--nounixsocket` applies only
   to Unix-based systems.

   The :program:`mongod` process
   always listens on the UNIX socket unless one of the following is true:
   
   - :option:`--nounixsocket` is set
   
   - :setting:`net.bindIp` is not set
   
   - :setting:`net.bindIp` does not specify ``localhost`` or its associated IP address
   
   .. |mongodb-package| replace:: :program:`mongod`
   
   .. include:: /includes/note-deb-and-rpm-default-to-localhost.rst


.. option:: --unixSocketPrefix <path>

   *Default*: /tmp

   The path for the UNIX socket. :option:`--unixSocketPrefix` applies only
   to Unix-based systems.
   
   If this option has no value, the
   :program:`mongod` process creates a socket with ``/tmp`` as a prefix. MongoDB
   creates and listens on a UNIX socket unless one of the following is true:
   
   - :setting:`net.unixDomainSocket.enabled` is ``false``
   
   - :option:`--nounixsocket` is set
   
   - :setting:`net.bindIp` is not set
   
   - :setting:`net.bindIp` does not specify ``localhost`` or its associated IP address


.. option:: --filePermissions <path>

   *Default*: ``0700``

   Sets the permission for the UNIX domain socket file.
   
   :option:`--filePermissions` applies only to Unix-based systems.


.. option:: --fork

   Enables a :term:`daemon` mode that runs the :program:`mongod` process in the
   background. By default :program:`mongod` does not run as a daemon:
   typically you will run :program:`mongod` as a daemon, either by using
   :option:`--fork` or by using a controlling process that handles the
   daemonization process (e.g. as with ``upstart`` and ``systemd``).
   
   Using the :option:`--fork` option requires that you configure log
   output for the :program:`mongod` with one of the following:

   - :option:`--logpath`
   - :option:`--syslog`

   The :option:`--fork` option is not supported on Windows.


.. option:: --auth

   Enables authorization to control user's access to database resources
   and operations. When authorization is enabled, MongoDB requires all
   clients to authenticate themselves first in order to determine the
   access for the client.
   
   Configure users via the :doc:`mongo shell
   </reference/program/mongo>`. If no users exist, the localhost interface
   will continue to have access to the database until you create
   the first user.
   
   See :doc:`Security </security>`
   for more information.
   


.. option:: --noauth

   Disables authentication. Currently the default. Exists for future
   compatibility and clarity.
   


.. option:: --transitionToAuth

   .. versionadded:: 3.4
   
      Allows the :program:`mongod` to accept and create authenticated and
      non-authenticated connections to and from other :binary:`~bin.mongod`
      and :binary:`~bin.mongos` instances in the deployment. Used for
      performing rolling transition of replica sets or sharded clusters
      from a no-auth configuration to :ref:`internal authentication
      <inter-process-auth>`. Requires specifying a :ref:`internal
      authentication <inter-process-auth>` mechanism such as
      :option:`--keyFile`.
   
   For example, if using :ref:`keyfiles <internal-auth-keyfile>` for
   :ref:`internal authentication <inter-process-auth>`, the :program:`mongod` creates
   an authenticated connection with any :binary:`~bin.mongod` or :binary:`~bin.mongos`
   in the deployment using a matching keyfile. If the security mechanisms do
   not match, the :program:`mongod` utilizes a non-authenticated connection instead.
   
   A :program:`mongod` running with :option:`--transitionToAuth` does not enforce :ref:`user access
   controls <authorization>`. Users may connect to your deployment without any
   access control checks and perform read, write, and administrative operations.
   
   .. note::
   
      A :program:`mongod` running with :ref:`internal authentication
      <inter-process-auth>` and *without* :option:`--transitionToAuth` requires clients to connect
      using :ref:`user access controls <authorization>`. Update clients to
      connect to the :program:`mongod` using the appropriate :ref:`user <users>`
      prior to restarting :program:`mongod` without :option:`--transitionToAuth`.


.. option:: --cpu

   Forces the :program:`mongod` process to report the percentage of CPU time in
   write lock, every four seconds.


.. option:: --sysinfo

   Returns diagnostic system information and then exits. The
   information provides the page size, the number of physical pages,
   and the number of available physical pages.
   


.. option:: --noscripting

   Disables the scripting engine.
   


.. option:: --notablescan

   Forbids operations that require a collection scan. See :parameter:`notablescan` for additional information.
   


.. option:: --shutdown

   The :option:`--shutdown` option cleanly and safely terminates the :program:`mongod`
   process. When invoking :program:`mongod` with this option you must set the
   :option:`--dbpath` option either directly or by way of the
   :doc:`configuration file </reference/configuration-options>` and the
   :option:`--config` option.
   
   The :option:`--shutdown` option is available only on Linux systems.

   For additional ways to shut down, see also :ref:`terminate-mongod-processes`.
   


.. option:: --redactClientLogData

   .. versionadded:: 3.4 Available in MongoDB Enterprise only.
   
   A :program:`mongod` running with :option:`--redactClientLogData` redacts any message accompanying a given
   log event before logging. This prevents the :program:`mongod` from writing
   potentially sensitive data stored on the database to the diagnostic log.
   Metadata such as error or operation codes, line numbers, and source file
   names are still visible in the logs.
   
   Use :option:`--redactClientLogData` in conjunction with
   :doc:`/core/security-encryption-at-rest` and
   :doc:`/core/security-transport-encryption` to assist compliance with
   regulatory requirements.
   
   For example, a MongoDB deployment might store Personally Identifiable
   Information (PII) in one or more collections. The :program:`mongod` logs events
   such as those related to CRUD operations, sharding metadata, etc. It is
   possible that the :program:`mongod` may expose PII as a part of these logging
   operations. A :program:`mongod` running with :option:`--redactClientLogData` removes any message
   accompanying these events before being output to the log, effectively
   removing the PII.
   
   Diagnostics on a :program:`mongod` running with :option:`--redactClientLogData` may be more difficult
   due to the lack of data related to a log event. See the
   :ref:`process logging <monitoring-log-redaction>` manual page for an
   example of the effect of :option:`--redactClientLogData` on log output.
   
   On a running :program:`mongod`, use :dbcommand:`setParameter` with the
   :parameter:`redactClientLogData` parameter to configure this setting.


.. option:: --networkMessageCompressors <string>

   *Default*: snappy

   
   .. versionadded:: 3.4
   
   Specifies the default compressor(s) to use for
   communication between this :program:`mongod` instance and:
   
   - other members of the deployment if the instance is part of a replica set or a sharded cluster
   
   - a :binary:`~bin.mongo` shell
   
   - drivers that support the ``OP_COMPRESSED`` message format.
   
   MongoDB supports the following compressors:
   
   - :term:`snappy`
   
   - :term:`zlib` (Available in MongoDB 3.6 or greater)
   
   **In versions 3.6 and 4.0**, :binary:`~bin.mongod` and
   :binary:`~bin.mongos` enable network compression by default with
   ``snappy`` as the compressor.
   
   To disable network compression, set the value to ``disabled``.
   
   .. include:: /includes/fact-networkMessageCompressors.rst


.. option:: --timeZoneInfo <path>

   .. include:: /includes/fact-timeZoneInfo.rst
   
   .. code-block:: sh
   
      wget https://downloads.mongodb.org/olson_tz_db/timezonedb-latest.zip
      unzip timezonedb-latest.zip
      mongod --timeZoneInfo timezonedb-2017b/

   .. include::  /includes/warning-timeZoneInfo.rst

   .. seealso::
   
      :setting:`processManagement.timeZoneInfo`.


.. option:: --serviceExecutor <string>

   *Default*: synchronous

   .. versionadded:: 3.6
   
   Determines the threading and execution model :program:`mongod` uses to
   execute client requests. The ``--serviceExecutor`` option accepts one
   of the following values:
   
   .. list-table::
      :header-rows: 1
      :widths: 20 40
   
      * - Value
   
        - Description
   
      * - ``synchronous``
   
        - The :program:`mongod` uses synchronous networking and manages its
          networking thread pool on a per connection basis. Previous
          versions of MongoDB managed threads in this way.
   
      * - ``adaptive``
   
        - The :program:`mongod` uses the new experimental asynchronous
          networking mode with an adaptive thread pool which manages
          threads on a per request basis. This mode should have more
          consistent performance and use less resources when there are
          more inactive connections than database requests.


Free Monitoring
~~~~~~~~~~~~~~~

.. versionadded:: 4.0

.. option:: --enableFreeMonitoring <runtime|on|off>

   
   .. versionadded:: 4.0
   
      Available for MongoDB Community Edition.
   
   Enables or disables :doc:`free MongoDB Cloud monitoring
   </administration/free-monitoring>`. :option:`--enableFreeMonitoring` accepts the following
   values:
   
   .. list-table::
      :widths: 20 80
   
      * - ``runtime`` 
   
        - Default. You can enable or disable free monitoring during
          runtime.
   
          To enable or disable free monitoring during runtime, see
          :method:`db.enableFreeMonitoring()` and
          :method:`db.disableFreeMonitoring()`.
   
          To enable or disable free monitoring during runtime when
          running with access control, users must have required
          privileges. See :method:`db.enableFreeMonitoring()` and
          :method:`db.disableFreeMonitoring()` for details.
   
      * - ``on``
   
        - Enables free monitoring at startup; i.e. registers for free
          monitoring. When enabled at startup, you cannot disable free
          monitoring during runtime.
   
      * - ``off`` 
   
        - Disables free monitoring at startup, regardless of whether
          you have previously registered for free monitoring.  When disabled at startup,
          you cannot enable free monitoring during runtime.
   
   Once enabled, the free monitoring state remains enabled until
   explicitly disabled. That is, you do not need to re-enable each time
   you start the server.

   
   For the corresponding configuration file setting, see
   :setting:`cloud.monitoring.free.state`.
   


.. option:: --freeMonitoringTag <string>

   
   .. versionadded:: 4.0
   
      Available for MongoDB Community Edition.
   
   Optional tag to describe environment context. The tag can be sent as
   part of the :doc:`free MongoDB Cloud monitoring
   </administration/free-monitoring>` registration at start up.
   

   
   For the corresponding configuration file setting, see
   :setting:`cloud.monitoring.free.tags`.
   



LDAP Authentication or Authorization Options
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. option:: --ldapServers <host1>:<port>,<host2>:<port>,...,<hostN>:<port>

   .. versionadded:: 3.4 Available in MongoDB Enterprise only.
   
   The LDAP server against which the :program:`mongod` authenticates users or
   determines what actions a user is authorized to perform on a given
   database. If the LDAP server specified has any replicated instances,
   you may specify the host and port of each replicated server in a
   comma-delimited list.
   
   If your LDAP infrastructure partitions the LDAP directory over multiple LDAP
   servers, specify *one* LDAP server or any of its replicated instances to
   :option:`--ldapServers`. MongoDB supports following LDAP referrals as defined in `RFC 4511
   4.1.10 <https://www.rfc-editor.org/rfc/rfc4511.txt>`_. Do not use :option:`--ldapServers`
   for listing every LDAP server in your infrastructure.
   
   This setting can be configured on a running :program:`mongod` using
   :dbcommand:`setParameter`.
   
   If unset, :program:`mongod` cannot use :doc:`LDAP authentication or authorization
   </core/security-ldap>`.

.. option:: --ldapValidateLDAPServerConfig <boolean>

   *Available in MongoDB Enterprise*

   A flag that determines if the :binary:`~bin.mongod` instance checks
   the availability of the :option:`LDAP server(s)
   <mongod --ldapServers>` as part of its startup:

   - If ``true``, the :binary:`~bin.mongod` instance performs the
     availability check and only continues to start up if the LDAP
     server is available.

   - If ``false``, the :binary:`~bin.mongod` instance skips the
     availability check; i.e. the instance starts up even if the LDAP
     server is unavailable.

.. option:: --ldapQueryUser <string>

   .. versionadded:: 3.4 Available in MongoDB Enterprise only.
   
   The identity with which :program:`mongod` binds as, when connecting to or
   performing queries on an LDAP server.
   
   Only required if any of the following are true:
   
   - Using :ref:`LDAP authorization <security-ldap-external>`.
   - Using an LDAP query for :option:`username transformation <--ldapUserToDNMapping>`.
   - The LDAP server disallows anonymous binds
   
   You must use :option:`--ldapQueryUser` with :option:`--ldapQueryPassword`.
   
   If unset, :program:`mongod` will not attempt to bind to the LDAP server.
   
   This setting can be configured on a running :program:`mongod` using
   :dbcommand:`setParameter`.
   
   .. note::
   
      Windows MongoDB deployments can use :option:`--ldapBindWithOSDefaults`
      instead of :option:`--ldapQueryUser` and :option:`--ldapQueryPassword`. You cannot specify
      both :option:`--ldapQueryUser` and :option:`--ldapBindWithOSDefaults` at the same time.


.. option:: --ldapQueryPassword <string>

   .. versionadded:: 3.4 Available in MongoDB Enterprise only.
   
   The password used to bind to an LDAP server when using
   :option:`--ldapQueryUser`. You must use :option:`--ldapQueryPassword` with
   :option:`--ldapQueryUser`.
   
   If unset, :program:`mongod` will not attempt to bind to the LDAP server.
   
   This setting can be configured on a running :program:`mongod` using
   :dbcommand:`setParameter`.
   
   .. note::
   
      Windows MongoDB deployments can use :option:`--ldapBindWithOSDefaults`
      instead of :option:`--ldapQueryPassword` and :option:`--ldapQueryPassword`. You cannot specify
      both :option:`--ldapQueryPassword` and :option:`--ldapBindWithOSDefaults` at the same time.


.. option:: --ldapBindWithOSDefaults <bool>

   *Default*: false

   .. versionadded:: 3.4
   
      Available in MongoDB Enterprise for the Windows platform only.
   
   Allows :program:`mongod` to authenticate, or bind, using your Windows login
   credentials when connecting to the LDAP server.
   
   Only required if:
   
   - Using :ref:`LDAP authorization <security-ldap-external>`.
   - Using an LDAP query for :option:`username transformation <--ldapUserToDNMapping>`.
   - The LDAP server disallows anonymous binds
   
   Use :option:`--ldapBindWithOSDefaults` to replace :option:`--ldapQueryUser` and
   :option:`--ldapQueryPassword`.


.. option:: --ldapBindMethod <string>

   *Default*: simple

   .. versionadded:: 3.4 Available in MongoDB Enterprise only.
   
   The method :program:`mongod` uses to authenticate to an LDAP server.
   Use with :option:`--ldapQueryUser` and :option:`--ldapQueryPassword` to
   connect to the LDAP server.
   
   :option:`--ldapBindMethod` supports the following values:
   
   * ``simple`` - :program:`mongod` uses simple authentication.
   
   * ``sasl`` - :program:`mongod` uses SASL protocol for authentication
   
   If you specify ``sasl``, you can configure the available SASL mechanisms
   using :option:`--ldapBindSaslMechanisms`. :program:`mongod` defaults to
   using ``DIGEST-MD5`` mechanism.


.. option:: --ldapBindSaslMechanisms <string>

   *Default*: DIGEST-MD5

   .. versionadded:: 3.4 Available in MongoDB Enterprise only.
   
   A comma-separated list of SASL mechanisms :program:`mongod` can
   use when authenticating to the LDAP server. The :program:`mongod` and the
   LDAP server must agree on at least one mechanism. The :program:`mongod`
   dynamically loads any SASL mechanism libraries installed on the host
   machine at runtime.
   
   Install and configure the appropriate libraries for the selected
   SASL mechanism(s) on both the :program:`mongod` host and the remote
   LDAP server host. Your operating system may include certain SASL
   libraries by default. Defer to the documentation associated with each
   SASL mechanism for guidance on installation and configuration.
   
   If using the ``GSSAPI`` SASL mechanism for use with
   :ref:`security-kerberos`, verify the following for the
   :program:`mongod` host machine:
   
   ``Linux``
     - The ``KRB5_CLIENT_KTNAME`` environment
       variable resolves to the name of the client :ref:`keytab-files`
       for the host machine. For more on Kerberos environment
       variables, please defer to the
       `Kerberos documentation <https://web.mit.edu/kerberos/krb5-1.13/doc/admin/env_variables.html>`__.
     - The client keytab includes a
       :ref:`kerberos-user-principal` for the :program:`mongod` to use when
       connecting to the LDAP server and execute LDAP queries.
   
   ``Windows``
     If connecting to an Active Directory server, the Windows
     Kerberos configuration automatically generates a
     `Ticket-Granting-Ticket <https://msdn.microsoft.com/en-us/library/windows/desktop/aa380510(v=vs.85).aspx>`__
     when the user logs onto the system. Set :option:`--ldapBindWithOSDefaults` to
     ``true`` to allow :program:`mongod` to use the generated credentials when
     connecting to the Active Directory server and execute queries.
   
   Set :option:`--ldapBindMethod` to ``sasl`` to use this option.
   
   .. note::
   
      For a complete list of SASL mechanisms see the
      `IANA listing
      <http://www.iana.org/assignments/sasl-mechanisms/sasl-mechanisms.xhtml>`_.
      Defer to the documentation for your LDAP or Active Directory
      service for identifying the SASL mechanisms compatible with the
      service.
   
      MongoDB is not a source of SASL mechanism libraries, nor
      is the MongoDB documentation a definitive source for
      installing or configuring any given SASL mechanism. For
      documentation and support, defer to the SASL mechanism
      library vendor or owner.
   
      For more information on SASL, defer to the following resources:
   
      - For Linux, please see the `Cyrus SASL documentation <https://www.cyrusimap.org/sasl/>`__.
      - For Windows, please see the `Windows SASL documentation <https://msdn.microsoft.com/en-us/library/cc223500.aspx>`__.


.. option:: --ldapTransportSecurity <string>

   *Default*: tls

   .. versionadded:: 3.4 Available in MongoDB Enterprise only.
   
   By default, :program:`mongod` creates a TLS/SSL secured connection to the LDAP
   server.
   
   For Linux deployments, you must configure the appropriate TLS Options in
   ``/etc/openldap/ldap.conf`` file. Your operating system's package manager
   creates this file as part of the MongoDB Enterprise installation, via the
   ``libldap`` dependency. See the documentation for ``TLS Options`` in the
   `ldap.conf OpenLDAP documentation
   <http://www.openldap.org/software/man.cgi?query=ldap.conf&manpath=OpenLDAP+2.4-Release>`_
   for more complete instructions.
   
   For Windows deployment, you must add the LDAP server CA certificates to the
   Windows certificate management tool. The exact name and functionality of the
   tool may vary depending on operating system version. Please see the
   documentation for your version of Windows for more information on
   certificate management.
   
   Set :option:`--ldapTransportSecurity` to ``none`` to disable TLS/SSL between :program:`mongod` and the LDAP
   server.
   
   .. warning::
   
      Setting :option:`--ldapTransportSecurity` to ``none`` transmits plaintext information and possibly
      credentials between :program:`mongod` and the LDAP server.


.. option:: --ldapTimeoutMS <long>

   *Default*: 10000

   .. versionadded:: 3.4 Available in MongoDB Enterprise only.
   
   The amount of time in milliseconds :program:`mongod` should wait for an LDAP server
   to respond to a request.
   
   Increasing the value of :option:`--ldapTimeoutMS` may prevent connection failure between the
   MongoDB server and the LDAP server, if the source of the failure is a
   connection timeout. Decreasing the value of :option:`--ldapTimeoutMS` reduces the time
   MongoDB waits for a response from the LDAP server.
   
   This setting can be configured on a running :program:`mongod` using
   :dbcommand:`setParameter`.


.. option:: --ldapUserToDNMapping <string>

   .. versionadded:: 3.4 Available in MongoDB Enterprise only.
   
   Maps the username provided to :program:`mongod` for authentication to a LDAP
   Distinguished Name (DN). You may need to use :option:`--ldapUserToDNMapping` to transform a
   username into an LDAP DN in the following scenarios:
   
   - Performing LDAP authentication with simple LDAP binding, where users
     authenticate to MongoDB with usernames that are not full LDAP DNs.
   
   - Using an :option:`LDAP authorization query template
     <mongod --ldapAuthzQueryTemplate>` that requires a DN.
   
   - Transforming the usernames of clients authenticating to Mongo DB using
     different authentication mechanisms (e.g. x.509, kerberos) to a full LDAP
     DN for authorization.
   
   :option:`--ldapUserToDNMapping` expects a quote-enclosed JSON-string representing an ordered array
   of documents. Each document contains a regular expression ``match`` and
   either a ``substitution`` or ``ldapQuery`` template used for transforming the
   incoming username.
   
   Each document in the array has the following form:
   
   .. code-block:: javascript
   
      {
        match: "<regex>"
        substitution: "<LDAP DN>" | ldapQuery: "<LDAP Query>"
      }
   
   .. list-table::
      :header-rows: 1
      :widths: 10 70 20
   
      * - Field
        - Description
        - Example
   
      * - ``match``
        - An ECMAScript-formatted regular expression (regex) to match against a
          provided username. Each parenthesis-enclosed section represents a
          regex capture group used by ``substitution`` or ``ldapQuery``.
        - ``"(.+)ENGINEERING"``
          ``"(.+)DBA"``
   
      * - ``substitution``
   
        - An LDAP distinguished name (DN) formatting template that converts the
          authentication name matched by the ``match`` regex into a LDAP DN.
          Each curly bracket-enclosed numeric value is replaced by the
          corresponding `regex capture group
          <http://www.regular-expressions.info/refcapture.html>`_ extracted
          from the authentication username via the ``match`` regex.
          
          The result of the substitution must be an `RFC4514
          <https://www.ietf.org/rfc/rfc4514.txt>`_ escaped string.
   
        - ``"cn={0},ou=engineering,
          dc=example,dc=com"``
   
      * - ``ldapQuery``
   
        - A LDAP query formatting template that inserts the authentication
          name matched by the ``match`` regex into an LDAP query URI encoded
          respecting RFC4515 and RFC4516. Each curly bracket-enclosed numeric
          value is replaced by the corresponding `regex capture group
          <http://www.regular-expressions.info/refcapture.html>`_ extracted
          from the authentication username via the ``match`` expression.
          :program:`mongod` executes the query against the LDAP server to retrieve
          the LDAP DN for the authenticated user. :program:`mongod` requires
          exactly one returned result for the transformation to be
          successful, or :program:`mongod` skips this transformation.
   
        - ``"ou=engineering,dc=example,
          dc=com??one?(user={0})"``
   
   .. note::
   
      An explanation of  `RFC4514 <https://www.ietf.org/rfc/rfc4514.txt>`_,
      `RFC4515 <https://tools.ietf.org/search/rfc4515>`_,
      `RFC4516 <https://tools.ietf.org/html/rfc4516>`_, or LDAP queries is out
      of scope for the MongoDB Documentation. Please review the RFC directly or
      use your preferred LDAP resource.
   
   For each document in the array, you must use either ``substitution`` or
   ``ldapQuery``. You *cannot* specify both in the same document.
   
   When performing authentication or authorization, :program:`mongod` steps through
   each document in the array in the given order, checking the authentication
   username against the ``match`` filter.  If a match is found,
   :program:`mongod` applies the transformation and uses the output for
   authenticating the user. :program:`mongod` does not check the remaining documents
   in the array.
   
   If the given document does not match the provided authentication name, or
   the transformation described by the document fails, :program:`mongod` continues
   through the list of documents to find additional matches. If no matches are
   found in any document, :program:`mongod` returns an error.
   
   .. example::
   
     The following shows two transformation documents. The first
     document matches against any string ending in ``@ENGINEERING``, placing
     anything preceeding the suffix into a regex capture group. The
     second document matches against any string ending in ``@DBA``, placing
     anything preceeding the suffix into a regex capture group.
   
     .. important::  You must pass the array to :option:`--ldapUserToDNMapping` as a string.
   
     .. code-block:: text
   
        "[
           {
              match: "(.+)@ENGINEERING.EXAMPLE.COM",
              substitution: "cn={0},ou=engineering,dc=example,dc=com"
           },
           {
              match: "(.+)@DBA.EXAMPLE.COM",
              ldapQuery: "ou=dba,dc=example,dc=com??one?(user={0})"
   
           }
   
        ]"
   
     A user with username ``alice@ENGINEERING.EXAMPLE.COM`` matches the first
     document. The regex capture group ``{0}`` corresponds to the string
     ``alice``. The resulting output is the DN
     ``"cn=alice,ou=engineering,dc=example,dc=com"``.
   
     A user with username ``bob@DBA.EXAMPLE.COM`` matches the second document.
     The regex capture group ``{0}`` corresponds to the string ``bob``.  The
     resulting output is the LDAP query
     ``"ou=dba,dc=example,dc=com??one?(user=bob)"``. :program:`mongod` executes this
     query against the LDAP server, returning the result
     ``"cn=bob,ou=dba,dc=example,dc=com"``.
   
   If :option:`--ldapUserToDNMapping` is unset, :program:`mongod` applies no transformations to the username
   when attempting to authenticate or authorize a user against the LDAP server.
   
   This setting can be configured on a running :program:`mongod` using the
   :dbcommand:`setParameter` database command.


.. option:: --ldapAuthzQueryTemplate <string>

   .. versionadded:: 3.4 Available in MongoDB Enterprise only.
   
   A relative LDAP query URL formatted conforming to `RFC4515
   <https://tools.ietf.org/search/rfc4515>`_ and `RFC4516
   <https://tools.ietf.org/html/rfc4516>`_ that :program:`mongod` executes to obtain
   the LDAP groups to which the authenticated user belongs to. The query is
   relative to the host or hosts specified in :option:`--ldapServers`.
   
   Use the ``{USER}`` placeholder in the URL to substitute the authenticated
   username, or the transformed username if a :option:`username mapping <--ldapUserToDNMapping>` is specified.
   
   When constructing the query URL, ensure that the order of LDAP parameters
   respects RFC4516:
   
   .. code-block:: shell
   
     [ dn  [ ? [attributes] [ ? [scope] [ ? [filter] [ ? [Extensions] ] ] ] ] ]
   
   If your query includes an attribute, :program:`mongod` assumes that the query
   retrieves a the DNs which this entity is member of.
   
   If your query does not include an attribute, :program:`mongod` assumes
   the query retrieves all entities which the user is member of.
   
   For each LDAP DN returned by the query, :program:`mongod` assigns the authorized
   user a corresponding role on the ``admin`` database. If a role on the on the
   ``admin`` database exactly matches the DN, :program:`mongod` grants the user the
   roles and privileges assigned to that role. See the
   :method:`db.createRole()` method for more information on creating roles.
   
   .. example::
   
     This LDAP query returns any groups listed in the LDAP user object's
     ``memberOf`` attribute.
   
     .. code-block:: shell
   
        "{USER}?memberOf?base"
   
     Your LDAP configuration may not include the ``memberOf`` attribute as part
     of the user schema, may possess a different attribute for reporting group
     membership, or may not track group membership through attributes.
     Configure your query with respect to your own unique LDAP configuration.
   
   If unset, :program:`mongod` cannot authorize users using LDAP.
   
   This setting can be configured on a running :program:`mongod` using the
   :dbcommand:`setParameter` database command.
   
   .. note::
   
      An explanation of `RFC4515 <https://tools.ietf.org/search/rfc4515>`_,
      `RFC4516 <https://tools.ietf.org/html/rfc4516>`_ or LDAP queries is out
      of scope for the MongoDB Documentation. Please review the RFC directly or
      use your preferred LDAP resource.


Storage Options
~~~~~~~~~~~~~~~

.. option:: --storageEngine string

   *Default*: ``wiredTiger``

   
   .. versionchanged:: 4.0
   
      MongoDB deprecates the MMAPv1 storage engine.
   
   Specifies the storage engine for the :program:`mongod` database. Available
   values include:
   
   .. list-table::
      :header-rows: 1
      :widths: 20 80
   
      * - Value
        - Description
   
      * - ``wiredTiger``
        - To specify the :doc:`/core/wiredtiger`.
   
      * - ``inMemory``
   
        - To specify the :doc:`/core/inmemory`.
   
          .. versionadded:: 3.2
             Available in MongoDB Enterprise only.
   
      * - ``mmapv1`` (Deprecated in MongoDB 4.0)
        - To specify the :doc:`/core/mmapv1`.

   If you attempt to start a :program:`mongod` with a
   :option:`--dbpath` that contains data files produced by a
   storage engine other than the one specified by :option:`--storageEngine`, :program:`mongod`
   will refuse to start.


.. option:: --dbpath <path>

   *Default*: ``/data/db`` on Linux and macOS, ``\data\db`` on Windows

   The directory where the :program:`mongod` instance stores its data.

   If using the default
   :doc:`configuration file </reference/configuration-options>`
   included with a package manager installation of MongoDB, the
   corresponding :setting:`storage.dbPath` setting uses a different
   default.

   .. versionchanged:: 3.0
      The files in :option:`--dbpath` must correspond to the storage engine
      specified in :option:`--storageEngine`. If the data files do not
      correspond to :option:`--storageEngine`, :program:`mongod` will refuse to
      start.


.. option:: --directoryperdb

   Uses a separate directory to store data for each database. The
   directories are under the :option:`--dbpath` directory, and each subdirectory
   name corresponds to the database name.
   
   .. versionchanged:: 3.0
   
      To change the :option:`--directoryperdb` option for existing deployments, you must
      restart the :binary:`~bin.mongod` instances with the new :option:`--directoryperdb`
      value **and** a new data directory (:option:`--dbpath \<new path\> <--dbpath>`), and then
      repopulate the data.
   
      - For standalone instances, you can use :binary:`~bin.mongodump` on
        the existing instance, stop the instance, restart with the new
        :option:`--directoryperdb` value **and** a new data directory, and use
        :binary:`~bin.mongorestore` to populate the new data directory.
   
      - For replica sets, you can update in a rolling manner by stopping
        a secondary member, restart with the new :option:`--directoryperdb` value **and**
        a new data directory, and use :ref:`initial sync
        <replica-set-initial-sync>` to populate the new data directory.
        To update all members, start with the secondary members first.
        Then step down the primary, and update the stepped-down member.

   .. include:: /includes/not-available-for-inmemory-storage-engine.rst
   


.. option:: --noIndexBuildRetry

   
   .. versionchanged:: 4.0
   
      :option:`--noIndexBuildRetry` cannot be used in
      conjunction with :option:`--replSet <mongod --replSet>`; i.e., you cannot
      use :option:`--noIndexBuildRetry` for a :binary:`~bin.mongod` instance that is part of
      a replica set.
   
   Stops the :program:`mongod` **standalone** instance from rebuilding incomplete indexes on the next
   start up. This applies in cases where the :program:`mongod` restarts after it
   has shut down or stopped in the middle of an index build. In such cases,
   the :program:`mongod` always removes any incomplete indexes, and then also, by
   default, attempts to rebuild them. To stop the :program:`mongod` from
   rebuilding incomplete indexes on start up, include this option on the
   command-line.
   
   The :option:`--noIndexBuildRetry` only applies to standalones.

   .. include:: /includes/not-available-for-inmemory-storage-engine.rst
   


.. option:: --noprealloc

   
   *Only available for the MMAPv1 storage engine.*
   
   .. deprecated:: 2.6
   
      By default, MongoDB does not preallocate data files. The option
      exists for compatibility.
   
   Disables the preallocation of data files.
   


.. option:: --nssize <value>

   *Default*: 16

   
   *Only available for the MMAPv1 storage engine.*
   
   Specifies the default size for namespace files, which are files that end
   in ``.ns``. Each collection and index counts as a namespace.
   
   Use this setting to control size for newly created namespace files. This
   option has no impact on existing files. The maximum size for a namespace
   file is 2047 megabytes. The default value of 16 megabytes provides for
   approximately 24,000 namespaces.


.. option:: --quota

   *Only available for the MMAPv1 storage engine.*
   
   Enables a maximum limit for the number data files each database can
   have. When running with the :option:`--quota` option, MongoDB has a maximum of 8
   data files per database. Adjust the quota with
   :option:`--quotaFiles`.


.. option:: --quotaFiles <number>

   *Default*: 8

   *Only available for the MMAPv1 storage engine.*
   
   Modifies the limit on the number of data files per database. :option:`--quotaFiles`
   option requires that you set :option:`--quota`.


.. option:: --smallfiles

   
   *Only available for the MMAPv1 storage engine.*
   
   Sets MongoDB to use a smaller default file size. The :option:`--smallfiles` option
   reduces the initial size for data files and limits the maximum size to
   512 megabytes. :option:`--smallfiles` also reduces the size of each :term:`journal`
   file from 1 gigabyte to 128 megabytes. Use :option:`--smallfiles` if you have a large
   number of databases that each holds a small quantity of data.
   
   The :option:`--smallfiles` option can lead the :program:`mongod` instance to create a large
   number of files, which can affect performance for larger databases.


.. option:: --syncdelay <value>

   *Default*: 60

   Controls how much time can pass before MongoDB flushes data to the data
   files via an :term:`fsync` operation.
   
   **Do not set this value on
   production systems.** In almost every situation, you should use the
   default setting.
   
   .. warning::
   
      If you set :option:`--syncdelay` to ``0``, MongoDB will not sync the
      memory mapped files to disk.
   
   The :program:`mongod` process writes data very quickly to the journal and
   lazily to the data files. :option:`--syncdelay` has no effect on the
   :setting:`journal <storage.journal.enabled>` files or :doc:`journaling </core/journaling>`,
   but if :option:`--syncdelay` is set to ``0`` the journal will eventually consume
   all available disk space. If you set :option:`--syncdelay` to ``0`` for testing
   purposes, you should also set :option:`--nojournal <mongod --nojournal>`
   to ``true``.
   
   The :dbcommand:`serverStatus` command reports the background flush
   thread's status via the :serverstatus:`backgroundFlushing` field.

   .. include:: /includes/not-available-for-inmemory-storage-engine.rst
   


.. option:: --upgrade

   Upgrades the on-disk data format of the files specified by the
   :option:`--dbpath` to the latest version, if needed.
   
   This option only affects the operation of the :program:`mongod` if the data
   files are in an old format.
   
   In most cases you should not set this value, so you can exercise the
   most control over your upgrade process. See the MongoDB release notes
   for more information about the upgrade process.


.. option:: --repair

   
   .. versionchanged:: 4.0.3
   
   Runs a repair routine on all databases for a :binary:`~bin.mongod`
   instance. The operation attempts to salvage corrupt data as well as
   rebuilds all the indexes. The operation discards any corrupt data
   that cannot be salvaged.
   
   .. tip::
   
      .. include:: /includes/note-repair.rst
   
   .. include:: /includes/warning-repair.rst
   
   For MMAPv1 storage engine, see also :option:`--repairpath`.
   


.. option:: --repairpath <path>

   *Default*: A ``_tmp_repairDatabase_<num>`` directory under the
   :setting:`~storage.dbPath`.

   
   *Only available for the MMAPv1 storage engine.*
   
   Specifies a working directory that MongoDB will use during the
   :option:`--repair <mongod --repair>` operation. When ``--repair`` completes, the
   :option:`--repairpath` directory is empty, and
   :setting:`~storage.dbPath` contains the repaired files.

   The :option:`--repairpath` must be within the :setting:`~storage.dbPath`. You can
   specify a symlink to :option:`--repairpath` to use a path on a different file
   system.


.. option:: --journal

   Enables the durability :term:`journal` to ensure data files remain valid
   and recoverable. This option applies only when you specify the
   :option:`--dbpath` option. :program:`mongod` enables journaling by default.

   
   .. include:: /includes/not-available-for-inmemory-storage-engine.rst
   
   .. include:: /includes/extracts/no-journaling-writeConcernMajorityJournalDefault-false.rst
   
   .. include:: /includes/changes-inmem-startup-warning.rst
   


.. option:: --nojournal

   Disables :doc:`journaling </core/journaling>`. :program:`mongod`
   enables journaling by default.

   .. include:: /includes/not-available-for-inmemory-storage-engine.rst
   
   .. include:: /includes/wiredtiger-node-nojournal.rst
   


.. option:: --journalOptions <arguments>

   
   *Only available for the MMAPv1 storage engine.*
   
   Provides functionality for testing. Not for general use, and will affect data
   file integrity in the case of abnormal system shutdown.
   

   .. include:: /includes/not-available-for-inmemory-storage-engine.rst
   


.. option:: --journalCommitInterval <value>

   *Default*: 100 or 30

   
   .. versionchanged:: 3.2
   
   The maximum amount of time in milliseconds that
   the :program:`mongod` process allows between
   journal operations. Values can range from 1 to 500 milliseconds. Lower
   values increase the durability of the journal, at the expense of disk
   performance. The default journal commit interval is 100 milliseconds.
   
   On MMAPv1, if the journal is on a different block device (e.g. physical
   volume, RAID device, or LVM volume) than the data files, the default journal
   commit interval is 30 milliseconds. Additionally, on MMAPv1, when a write
   operation with ``j:true`` is pending, :program:`mongod` will reduce
   :setting:`~storage.journal.commitIntervalMs` to a third of the set value.
   
   On WiredTiger, the default journal commit interval is 100
   milliseconds. Additionally, a write that includes or implies
   ``j:true`` will cause an immediate sync of the journal. For details
   or additional conditions that affect the frequency of the sync for
   WiredTiger, see :ref:`journal-process`.

   .. include:: /includes/not-available-for-inmemory-storage-engine.rst
   


.. _cli-wiredtiger-options:

WiredTiger Options
~~~~~~~~~~~~~~~~~~

.. option:: --wiredTigerCacheSizeGB <float>

   
   Defines the maximum size of the internal cache that WiredTiger will
   use for all data. The memory consumed by an index build (see
   :parameter:`maxIndexBuildMemoryUsageMegabytes`) is separate from the
   WiredTiger cache memory. Starting in MongoDB 3.4, the values can range
   from 0.25 GB  to 10000 GB and can be a float.
   
   .. include:: /includes/extracts/wt-cache-default-setting.rst
   
   Avoid increasing the WiredTiger internal cache size above its
   default value.
   
   With WiredTiger, MongoDB utilizes both the WiredTiger internal cache
   and the filesystem cache.
   
   .. include:: /includes/extracts/wt-filesystem-cache.rst
   

   .. include:: /includes/extracts/wt-cache-additional-constraints-mongod-cmdline-option.rst
   


.. option:: --wiredTigerMaxCacheOverflowFileSizeGB <float>

   
   Specifies the maximum size (in GB) for the "lookaside (or cache
   overflow) table" file :file:`WiredTigerLAS.wt`.
   
   The setting can accept the following values:
   
   .. list-table::
      :header-rows: 1
      :widths: 20 80
   
      * - Value
        - Description
   
      * - ``0``
   
        - The default value. If set to ``0``, the file size is
          unbounded.
   
      * - number >= 0.1
   
        - The maximum size (in GB). If the :file:`WiredTigerLAS.wt`
          file exceeds this size, :binary:`~bin.mongod` exits with a
          fatal assertion. You can clear the :file:`WiredTigerLAS.wt`
          file and restart :binary:`~bin.mongod`.
   
   To change the maximum size during runtime, use the
   :parameter:`wiredTigerMaxCacheOverflowSizeGB` parameter.
   
   *Available in 4.0-series starting in 4.0.12*
   


.. option:: --wiredTigerJournalCompressor <compressor>

   *Default*: snappy

   
   .. versionadded:: 3.0.0
   
   Specifies the type of compression to use to compress WiredTiger
   journal data.
   
   Available compressors are:
   
   - ``none``
   
   - :term:`snappy`
   
   - :term:`zlib`
   
   For details on changing the journal compressor, see
   :ref:`manage-journaling-change-wt-journal-compressor`.


.. option:: --wiredTigerDirectoryForIndexes

   .. versionadded:: 3.0.0
   
   When you start :program:`mongod` with :option:`--wiredTigerDirectoryForIndexes`, :program:`mongod` stores indexes and collections in separate
   subdirectories under the data (i.e. :option:`--dbpath`) directory.
   Specifically, :program:`mongod` stores the indexes in a subdirectory named
   ``index`` and the collection data in a subdirectory named
   ``collection``.
   
   By using a symbolic link, you can specify a different location for
   the indexes. Specifically, when :binary:`~bin.mongod` instance is **not**
   running, move the ``index`` subdirectory to the destination and
   create a symbolic link named ``index`` under the data directory to
   the new destination.


.. option:: --wiredTigerCollectionBlockCompressor <compressor>

   *Default*: snappy

   
   .. versionadded:: 3.0.0
   
   Specifies the default type of compression to use to compress collection
   data. You can override this on a per-collection basis when creating
   collections.
   
   Available compressors are:
   
   - ``none``
   
   - :term:`snappy`
   
   - :term:`zlib`
   
   :option:`--wiredTigerCollectionBlockCompressor` affects all collections created. If you change
   the value of :option:`--wiredTigerCollectionBlockCompressor` on an existing MongoDB deployment, all new
   collections will use the specified compressor. Existing collections
   will continue to use the compressor specified when they were
   created, or the default compressor at that time.


.. option:: --wiredTigerIndexPrefixCompression <boolean>

   *Default*: true

   
   .. versionadded:: 3.0.0
   
   Enables or disables :term:`prefix compression` for index data.
   
   Specify ``true`` for :option:`--wiredTigerIndexPrefixCompression` to enable :term:`prefix compression` for
   index data, or ``false`` to disable prefix compression for index data.
   
   The :option:`--wiredTigerIndexPrefixCompression` setting affects all indexes created. If you change
   the value of :option:`--wiredTigerIndexPrefixCompression` on an existing MongoDB deployment, all new
   indexes will use prefix compression. Existing indexes
   are not affected.


.. _cli-mongod-replica-set:

Replication Options
~~~~~~~~~~~~~~~~~~~

.. option:: --replSet <setname>

   Configures replication. Specify a replica set name as an argument to
   this set. All hosts in the replica set must have the same set name.
   
   Starting in MongoDB 4.0,
   
   - :option:`--replSet` cannot be used in conjunction with
     :option:`--noIndexBuildRetry <mongod --noIndexBuildRetry >`.
   
   - For the WiredTiger storage engine, :option:`--replSet` cannot be used in
     conjunction with :option:`--nojournal <mongod --nojournal>`.
   
   .. include:: /includes/fact-unique-replica-set-names.rst


.. option:: --oplogSize <value>

   Specifies a maximum size in megabytes for the replication operation log
   (i.e., the :term:`oplog`).
   
   .. note:: 
   
      .. include:: /includes/fact-oplog-size.rst
   
   By default, the :program:`mongod` process creates an :term:`oplog` based on
   the maximum amount of space available. For 64-bit systems, the oplog
   is typically 5% of available disk space.
   
   Once the :program:`mongod` has created the oplog for the first time,
   changing the :option:`--oplogSize` option will not affect the size of the oplog.
   
   To change the oplog size of a running replica set member, use the
   :dbcommand:`replSetResizeOplog` administrative command.
   :dbcommand:`replSetResizeOplog` enables you to resize the oplog
   dynamically without restarting the :binary:`~bin.mongod` process.
   
   See :ref:`replica-set-oplog-sizing` for more information.


.. option:: --replIndexPrefetch

   *Default*: all

   .. |feature| replace:: :option:`--replIndexPrefetch`
   .. include:: /includes/fact-feature-is-mmapv1-only.rst
   
   Determines which indexes :term:`secondary` members of a :term:`replica
   set` load into memory before applying operations from the oplog. By
   default secondaries load all indexes related to an operation into memory
   before applying operations from the oplog.
   
   Set this option to one of the following:
   
   .. list-table::
      :header-rows: 1
      :widths: 20 40
   
      * - Value
   
        - Description
   
      * - ``none``
   
        - Secondaries do not load indexes into memory.
   
      * - ``all``
   
        - Secondaries load all indexes related to an operation.
   
      * - ``_id_only``
   
        - Secondaries load no additional indexes into memory beyond the
          already existing ``_id`` index.


.. option:: --enableMajorityReadConcern

   *Default*: true

   
   Starting in MongoDB 3.6, MongoDB enables support for
   :readconcern:`"majority"` read concern by default.
   
   For MongoDB 4.0.3+ and 3.6.1+, you can disable read concern
   :readconcern:`"majority"` to prevent the storage cache pressure from
   immobilizing a deployment with a three-member
   primary-secondary-arbiter (PSA) architecture. For more information
   about disabling read concern :readconcern:`"majority"`, see
   :ref:`4.0-disable-read-concern-majority`.
   
   To disable, set :option:`--enableMajorityReadConcern` to false.
   
   .. important::
   
      In general, avoid disabling :readconcern:`"majority"` read concern
      unless necessary. However, if you have a three-member replica set
      with a primary-secondary-arbiter (PSA) architecture or a sharded
      cluster with a three-member PSA shards, disable to prevent the
      storage cache pressure from immobilizing the deployment.
   
      Disabling :readconcern:`"majority"` read concern disables support
      for :doc:`/changeStreams`.
   
      Disabling :readconcern:`"majority"` does not affect
      :doc:`multi-document transactions </core/transactions>`; i.e. you
      can specify read concern "majority" for multi-document
      transactions even if read concern "majority" is disabled.
   
   :option:`--enableMajorityReadConcern` has no effect for MongoDB versions: 4.0.0, 4.0.1, 4.0.2, 3.6.0.


Sharded Cluster Options
~~~~~~~~~~~~~~~~~~~~~~~

.. option:: --configsvr

   
   *Required if starting a config server.*
   
   Declares that this :program:`mongod` instance serves as the :ref:`config
   server <sharded-cluster-config-server>` of a sharded cluster. When
   running with this option, clients (i.e. other cluster components)
   cannot write data to any database other than ``config``
   and ``admin``. The default port for a :program:`mongod` with this option is
   ``27019`` and the default :option:`--dbpath` directory is
   ``/data/configdb``, unless specified.
   
   .. important::
   
      Starting in 3.4, you must deploy config servers as a replica set.
      The use of the deprecated mirrored :binary:`~bin.mongod` instances as
      config servers (SCCC) is no longer supported.
   
      The replica set config servers (CSRS) must run the
      :doc:`WiredTiger storage engine </core/wiredtiger>`.
   
   The :option:`--configsvr` option creates a local :term:`oplog`.
   
   Do not use the :option:`--configsvr` option with :option:`--shardsvr`. Config
   servers cannot be a shard server.
   
   Do not use the :option:`--configsvr` with the
   :parameter:`skipShardingConfigurationChecks` parameter. That is, if
   you are temporarily starting the :binary:`~bin.mongod` as a
   standalone for maintenance operations, include the parameter
   :parameter:`skipShardingConfigurationChecks` and exclude :option:`--configsvr`.
   Once maintenance has completed, remove the
   :parameter:`skipShardingConfigurationChecks` parameter and restart
   with :option:`--configsvr`.


.. option:: --configsvrMode <string>

   **Available in MongoDB 3.2 version only**
   
   If set to ``sccc``, indicates that the config servers are deployed
   as three mirrored :binary:`~bin.mongod` instances, even if one or more
   config servers is also a member of a replica set. ``configsvrMode``
   only accepts the value ``sccc``.
   
   If unset, config servers running as replica sets expect to use the
   "config server replica set" protocol for writing to config servers,
   rather than the "mirrored mongod" write protocol.
   


.. option:: --shardsvr

   *Required if starting a shard server.*
   
   Configures this :program:`mongod` instance as a shard in a
   sharded cluster. The default port for these instances is
   ``27018``.
   
   .. important::
   
      Starting in MongoDB 3.6, you must deploy shards as replica sets. See the :option:`--replSet`
      option to deploy :program:`mongod` as part of a replica set.
   
   Do not use the :option:`--shardsvr` with the
   :parameter:`skipShardingConfigurationChecks` parameter. That is, if
   you are temporarily starting the :binary:`~bin.mongod` as a
   standalone for maintenance operations, include the parameter
   :parameter:`skipShardingConfigurationChecks` and exclude :option:`--shardsvr`.
   Once maintenance has completed, remove the
   :parameter:`skipShardingConfigurationChecks` parameter and restart
   with :option:`--shardsvr`.


.. option:: --moveParanoia

   If specified, during chunk migration, a shard saves,
   to the ``moveChunk`` directory of the ``--dbpath``, all documents
   migrated from that shard.
   
   MongoDB does not automatically delete the data saved in the
   ``moveChunk`` directory.


.. option:: --noMoveParanoia

   .. versionchanged:: 3.2
      Starting in 3.2, MongoDB uses ``--noMoveParanoia`` as the default.
   
   During chunk migration, a shard does not save documents migrated from
   the shard.



TLS/SSL Options
~~~~~~~~~~~~~~~

.. see:: :doc:`/tutorial/configure-ssl` for full
   documentation of MongoDB's support.

.. option:: --sslOnNormalPorts

   .. deprecated:: 2.6 Use :option:`--sslMode requireSSL <--sslMode>` instead.
   
   Enables TLS/SSL for :program:`mongod`.
   
   With :option:`--sslOnNormalPorts`, a :program:`mongod` requires TLS/SSL encryption for all
   connections on the default MongoDB port, or the port specified by
   :option:`--port`. By default, :option:`--sslOnNormalPorts` is
   disabled.
   
   .. include:: /includes/extracts/ssl-facts-see-more.rst


.. option:: --sslMode <mode>

   .. versionadded:: 2.6
   
   Enables TLS/SSL or mixed TLS/SSL used for all network connections. The
   argument to the :option:`--sslMode` option can be one of the following:
   
   .. list-table::
      :header-rows: 1
      :widths: 20 40
   
      * - Value
   
        - Description
   
      * - ``disabled``
   
        - The server does not use TLS/SSL.
   
      * - ``allowSSL``
   
        - Connections between servers do not use TLS/SSL. For incoming
          connections, the server accepts both TLS/SSL and non-TLS/non-SSL.
   
      * - ``preferSSL``
   
        - Connections between servers use TLS/SSL. For incoming
          connections, the server accepts both TLS/SSL and non-TLS/non-SSL.
   
      * - ``requireSSL``
   
        - The server uses and accepts only TLS/SSL encrypted connections.
   
   .. include:: /includes/extracts/ssl-facts-ca-file.rst
   
   .. include:: /includes/extracts/ssl-facts-see-more.rst


.. option:: --sslPEMKeyFile <filename>
   
   Specifies the :file:`.pem` file that contains both the TLS/SSL
   certificate and key.

   .. versionchanged:: 4.0

      Starting with MongoDB 4.0 on macOS or Windows, you can use the
      :option:`--sslCertificateSelector` option to specify a certificate
      from the operating system's secure certificate store instead of a
      PEM key file. :option:`--sslPEMKeyFile` and
      :option:`--sslCertificateSelector` options are mutually exclusive.
      You can only specify one.
   
   - On Linux/BSD, you must specify :option:`--sslPEMKeyFile` when
     TLS/SSL is enabled.
   
   - On Windows or macOS, you must specify either
     :option:`--sslPEMKeyFile` or :option:`--sslCertificateSelector`
     when TLS/SSL is enabled.

     .. important::

        For Windows **only**, MongoDB 4.0 and later do not support
        encrypted PEM files. The :binary:`~bin.mongod` fails to start if
        it encounters an encrypted PEM file. To securely store and
        access a certificate for use with TLS/SSL on Windows,
        use :option:`--sslCertificateSelector`.
   
   .. include:: /includes/extracts/ssl-facts-see-more.rst


.. option:: --sslPEMKeyPassword <value>

   Specifies the password to de-crypt the certificate-key file (i.e.
   :option:`--sslPEMKeyFile`). Use the :option:`--sslPEMKeyPassword` option only if the
   certificate-key file is encrypted. In all cases, the :program:`mongod` will
   redact the password from all logging and reporting output.
   
   Starting in MongoDB 4.0:
   
   - On Linux/BSD, if the private key in the PEM file is encrypted and
     you do not specify the :option:`--sslPEMKeyPassword` option, MongoDB will prompt for a
     passphrase. See :ref:`ssl-certificate-password`.
   
   - On macOS, if the private key in the PEM file is
     encrypted, you must explicitly specify the
     :option:`--sslPEMKeyPassword` option. Alternatively, you can use a
     certificate from the secure system store (see
     :option:`--sslCertificateSelector`) instead of a PEM key file or
     use an unencrypted PEM file.

   - On Windows, MongoDB does not support encrypted certificates.
     The :binary:`~bin.mongod` fails if it encounters an encrypted
     PEM file. Use :option:`--sslCertificateSelector` instead. 
   
   .. include:: /includes/extracts/ssl-facts-see-more.rst


.. COMMENT moved clusterAuthMode to here from above

.. option:: --clusterAuthMode <option>

   *Default*: keyFile

   .. versionadded:: 2.6
   
   The authentication mode used for cluster authentication. If you use
   :ref:`internal x.509 authentication <x509-internal-authentication>`,
   specify so here. This option can have one of the following values:
   
   .. list-table::
      :header-rows: 1
      :widths: 20 40
   
      * - Value
   
        - Description
   
      * - ``keyFile``
   
        - Use a keyfile for authentication.
          Accept only keyfiles.
   
      * - ``sendKeyFile``
   
        - For rolling upgrade purposes. Send a keyfile for
          authentication but can accept both keyfiles and x.509
          certificates.
   
      * - ``sendX509``
   
        - For rolling upgrade purposes. Send the x.509 certificate for
          authentication but can accept both keyfiles and x.509
          certificates.
   
      * - ``x509``
   
        - Recommended. Send the x.509 certificate for authentication and
          accept only x.509 certificates.
   
   .. include:: /includes/extracts/ssl-facts-ca-file.rst
   
   .. include:: /includes/extracts/ssl-facts-see-more.rst

.. option:: --sslClusterFile <filename>

   Specifies the :file:`.pem` file that contains the x.509
   certificate-key file for :ref:`membership authentication
   <x509-internal-authentication>` for the cluster or replica set.

   .. versionchanged:: 4.0

      Starting with MongoDB 4.0 on macOS or Windows, you can use the
      :option:`--sslClusterCertificateSelector` option to specify a
      certificate from the operating system's secure certificate store
      instead of a PEM key file. :option:`--sslClusterFile` and
      :option:`--sslClusterCertificateSelector` options are mutually
      exclusive. You can only specify one.
   
   If :option:`--sslClusterFile` does not specify the ``.pem`` file for
   internal cluster authentication or the alternative
   :option:`--sslClusterCertificateSelector`, the cluster uses the
   ``.pem`` file specified in the :option:`--sslPEMKeyFile` option or
   the certificate returned by the :option:`--sslCertificateSelector`.
   
   .. include:: /includes/extracts/ssl-facts-x509-ca-file.rst
   
   .. include:: /includes/extracts/ssl-facts-see-more.rst

   .. important::

      For Windows **only**, MongoDB 4.0 and later do not support
      encrypted PEM files. The :binary:`~bin.mongod` fails to start if
      it encounters an encrypted PEM file. To securely store and
      access a certificate for use with membership authentication on
      Windows, use :option:`--sslClusterCertificateSelector`.

.. option:: --sslCertificateSelector <parameter>=<value>
   
   .. versionadded:: 4.0

      Available on Windows and macOS as an alternative to
      :option:`--sslPEMKeyFile`. 

      Specifies a certificate property to select a matching certificate
      from the operating system's secure certificate store to use for
      TLS/SSL.
      
      :option:`--sslPEMKeyFile` and :option:`--sslCertificateSelector`
      options are mutually exclusive. You can only specify one.
   
   :option:`--sslCertificateSelector` accepts an argument of the format
   ``<property>=<value>`` where the property can be one of the
   following:
   
   .. include:: /includes/extracts/ssl-facts-certificate-selector-properties.rst
   
   .. include:: /includes/extracts/ssl-facts-certificate-selector-revocation.rst  

   The :binary:`~bin.mongod` searches the operating system's secure
   certificate store for the CA certificates required to validate the
   full certificate chain of the specified TLS/SSL certificate.
   Specifically, the secure certificate store must contain the root CA
   and any intermediate CA certificates required to build the full
   certificate chain to the TLS/SSL certificate. Do **not** use
   :option:`--sslCAFile` or :option:`--sslClusterCAFile` to specify the
   root and intermediate CA certificate
   
   For example, if the TLS/SSL certificate was signed with a single root
   CA certificate, the secure certificate store must contain that root
   CA certificate. If the TLS/SSL certificate was signed with an
   intermediate CA certificate, the secure certificate store must
   contain the intermedia CA certificate *and* the root CA certificate.

.. option:: --sslClusterCertificateSelector <parameter>=<value>

   .. versionadded:: 4.0
   
      Available on Windows and macOS as an alternative to
      :option:`--sslClusterFile`.
      
      Specifies a certificate property to select a matching certificate
      from the operating system's secure certificate store to use for
      :ref:`internal x.509 membership authentication
      <internal-auth-x509>`.

      :option:`--sslClusterFile` and
      :option:`--sslClusterCertificateSelector` options are mutually
      exclusive. You can only specify one.
   
   :option:`--sslClusterCertificateSelector` accepts an argument of the
   format ``<property>=<value>`` where the property can be one of the
   following:
   
   .. include:: /includes/extracts/ssl-facts-certificate-selector-properties.rst

   The :binary:`~bin.mongod` searches the operating system's secure
   certificate store for the CA certificates required to validate the
   full certificate chain of the specified cluster certificate.
   Specifically, the secure certificate store must contain the root CA
   and any intermediate CA certificates required to build the full
   certificate chain to the cluster certificate. Do **not** use
   :option:`--sslCAFile` or :option:`--sslClusterCAFile` to specify the
   root and intermediate CA certificate.
   
   For example, if the cluster certificate was signed with a single root
   CA certificate, the secure certificate store must contain that root
   CA certificate. If the cluster certificate was signed with an
   intermediate CA certificate, the secure certificate store must
   contain the intermedia CA certificate *and* the root CA certificate.

.. option:: --sslClusterPassword <value>

   .. versionadded:: 2.6
   
   Specifies the password to de-crypt the x.509 certificate-key file
   specified with ``--sslClusterFile``. Use the
   :option:`--sslClusterPassword` option only if the certificate-key
   file is encrypted. In all cases, the :program:`mongod` will redact
   the password from all logging and reporting output.
   
   Starting in MongoDB 4.0:
   
   - On Linux/BSD, if the private key in the x.509 file is encrypted and
     you do not specify the :option:`--sslClusterPassword` option,
     MongoDB will prompt for a passphrase. See
     :ref:`ssl-certificate-password`.
   
   - On macOS, if the private key in the x.509 file is encrypted, you
     must explicitly specify the :option:`--sslClusterPassword` option.
     Alternatively, you can either use a certificate from the secure
     system store (see :option:`--sslClusterCertificateSelector`)
     instead of a cluster PEM file or use an unencrypted PEM file.

   - On Windows, MongoDB does not support encrypted certificates.
     The :binary:`~bin.mongod` fails if it encounters an encrypted
     PEM file. Use :option:`--sslClusterCertificateSelector` instead.
   
   .. include:: /includes/extracts/ssl-facts-see-more.rst

.. option:: --sslCAFile <filename>

   Specifies the :file:`.pem` file that contains the root certificate
   chain from the Certificate Authority. Specify the file name of the
   :file:`.pem` file using relative or absolute paths.
   
   Windows/macOS Only
     If using :option:`--sslCertificateSelector` and/or
     :option:`--sslClusterCertificateSelector`, do **not** use
     :option:`--sslCAFile` to specify the root and intermediate CA
     certificates. Store all CA certificates required to validate the
     full trust chain of the :option:`--sslCertificateSelector` and/or
     :option:`--sslClusterCertificateSelector` certificates in the
     secure certificate store.
   
   .. include:: /includes/extracts/ssl-facts-see-more.rst

.. option:: --sslClusterCAFile <filename>

   .. versionadded:: 4.0.3
   
      Specifies the :file:`.pem` file that contains the root certificate
      chain from the Certificate Authority used to validate the
      certificate presented by a client establishing a connection.
      Specify the file name of the :file:`.pem` file using relative or
      absolute paths. :option:`--sslClusterCAFile` requires that
      :option:`--sslCAFile` is set.
   
   If :option:`--sslClusterCAFile` does not specify the :file:`.pem`
   file for validating the certificate from a client establishing a
   connection, the cluster uses the :file:`.pem` file specified in the
   :option:`--sslCAFile` option.
   
   :option:`--sslClusterCAFile` lets you use separate Certificate
   Authorities to verify the client to server and server to client
   portions of the TLS/SSL handshake.

   Windows/macOS Only
     If using :option:`--sslCertificateSelector` and/or
     :option:`--sslClusterCertificateSelector`, do **not** use
     :option:`--sslClusterCAFile` to specify the root and
     intermediate CA certificates. Store all CA certificates required to
     validate the full trust chain of the
     :option:`--sslCertificateSelector` and/or
     :option:`--sslClusterCertificateSelector` certificates in the
     secure certificate store.
   
   .. include:: /includes/extracts/ssl-facts-see-more.rst

.. option:: --sslCRLFile <filename>

   
   Specifies the :file:`.pem` file that contains the Certificate Revocation
   List. Specify the file name of the :file:`.pem` file using relative or
   absolute paths.
   
   .. note::
      
      Starting in MongoDB 4.0, you cannot specify :option:`--sslCRLFile` on macOS.  Use :option:`--sslCertificateSelector` instead.
   
   .. include:: /includes/extracts/ssl-facts-see-more.rst


.. option:: --sslAllowInvalidCertificates

   
   Bypasses the validation checks for TLS/SSL certificates on other
   servers in the cluster and allows the use of invalid certificates to
   connect.
   
   .. note::
   
      .. include:: /includes/extracts/ssl-facts-x509-invalid-certificate.rst
   
   When using
   the :option:`--sslAllowInvalidCertificates` setting, MongoDB
   logs a warning regarding the use of the invalid certificate.
   
   .. include:: /includes/extracts/ssl-facts-see-more.rst


.. option:: --sslAllowInvalidHostnames

   .. versionadded:: 3.0
   
   Disables the validation of the hostnames in TLS/SSL certificates,
   when connecting to other members of the replica set or sharded cluster
   for inter-process authentication. This allows :program:`mongod` to connect
   to other members if the hostnames in their certificates do not match
   their configured hostname.
   
   .. include:: /includes/extracts/ssl-facts-see-more.rst


.. option:: --sslAllowConnectionsWithoutCertificates

   For clients that do not present certificates, :program:`mongod` bypasses
   TLS/SSL certificate validation when establishing the connection.
   
   For clients that present a certificate, however, :program:`mongod` performs
   certificate validation using the root certificate chain specified by
   ``--sslCAFile`` and reject clients with invalid certificates.
   
   Use the :option:`--sslAllowConnectionsWithoutCertificates` option if you have a mixed deployment that includes
   clients that do not or cannot present certificates to the :program:`mongod`.
   
   .. include:: /includes/extracts/ssl-facts-see-more.rst


.. option:: --sslDisabledProtocols <protocol(s)>

   .. versionadded:: 3.0.7
   
   Prevents a MongoDB server running with TLS/SSL from accepting
   incoming connections that use a specific protocol or protocols. To
   specify multiple protocols, use a comma separated list of protocols.
    
   :option:`--sslDisabledProtocols` recognizes the following protocols: ``TLS1_0``, ``TLS1_1``,
   ``TLS1_2``, and starting in version 4.0.4 (and 3.6.9 and 3.4.24), ``TLS1_3``.
   
   - On macOS, you cannot disable ``TLS1_1`` and leave both ``TLS1_0`` and
     ``TLS1_2`` enabled. You must disable at least one of the other
     two, for example, ``TLS1_0,TLS1_1``.
   
   - To list multiple protocols, specify as a comma separated list of
     protocols. For example ``TLS1_0,TLS1_1``.
   
   - Specifying an unrecognized protocol will prevent the server from
     starting.
   
   - The specified disabled protocols overrides any default disabled
     protocols.
   
   Starting in version 4.0, MongoDB disables the use of TLS 1.0 if TLS
   1.1+ is available on the system. To enable the disabled TLS 1.0,
   specify ``none`` to :option:`--sslDisabledProtocols`. See :ref:`4.0-disable-tls`.
   
   Members of replica sets and sharded clusters must speak at least one
   protocol in common.
   
   .. seealso:: :ref:`ssl-disallow-protocols`


.. option:: --sslFIPSMode

   Directs the :program:`mongod` to use the FIPS mode of the  TLS/SSL
   library. Your system must have a FIPS
   compliant library to use the :option:`--sslFIPSMode` option.
   
   .. include:: /includes/note-fips-is-enterprise-only.rst



Profiler Options
~~~~~~~~~~~~~~~~

.. option:: --profile <level>

   *Default*: 0

   Configures the :doc:`database profiler
   </tutorial/manage-the-database-profiler>` level.
   The following profiler levels are available:
   
   .. include:: /includes/database-profiler-levels.rst
   
   .. include:: /includes/warning-profiler-performance.rst
   


.. option:: --slowms <integer>

   *Default*: 100

   
   .. include:: /includes/dbcommand-slowms-definition.rst
   

   For :binary:`~bin.mongod` instances, :option:`--slowms` affects the diagnostic log
   and, if enabled, the profiler.
   
   .. seealso:: :doc:`/tutorial/manage-the-database-profiler`


.. _cli-mongod-profiler-slowOpSampleRate:
.. option:: --slowOpSampleRate <double>

   *Default*: 1.0

   The fraction of *slow* operations that should be profiled or logged.
   :option:`--slowOpSampleRate` accepts values between 0 and 1, inclusive.
   
   :option:`--slowOpSampleRate` does not affect the :ref:`slow oplog entry logging
   <slow-oplog>` by the secondary members of a replica set. Secondary
   members log all oplog entries that take longer than the slow
   operation threshold regardless of the :option:`--slowOpSampleRate`.

   For :binary:`~bin.mongod` instances, :option:`--slowOpSampleRate` affects the
   diagnostic log and, if enabled, the profiler.


Audit Options
~~~~~~~~~~~~~

.. option:: --auditDestination

   
   Enables :doc:`auditing </core/auditing>` and specifies where
   :program:`mongod` sends all audit events.

   :option:`--auditDestination` can have one of the following values:
   
   .. list-table::
      :header-rows: 1
      :widths: 15 50
   
      * - Value
   
        - Description
   
      * - ``syslog``
   
        - Output the audit events to syslog in JSON format. Not available on
          Windows. Audit messages have a syslog severity level of ``info``
          and a facility level of ``user``.
   
          The syslog message limit can result in the truncation of
          audit messages. The auditing system will neither detect the
          truncation nor error upon its occurrence.
   
      * - ``console``
   
        - Output the audit events to ``stdout`` in JSON format.
   
      * - ``file``
   
        - Output the audit events to the file specified in
          :option:`--auditPath` in the format specified in
          :option:`--auditFormat`.
   
   .. include:: /includes/note-audit-in-enterprise-only.rst


.. option:: --auditFormat

   .. versionadded:: 2.6
   
   Specifies the format of the output file for :doc:`auditing
   </core/auditing>` if :option:`--auditDestination` is ``file``. The
   :option:`--auditFormat` option can have one of the following values:
   
   .. list-table::
      :header-rows: 1
      :widths: 15 50
   
      * - Value
   
        - Description
   
      * - ``JSON``
   
        - Output the audit events in JSON format to the file specified
          in :option:`--auditPath`.
   
      * - ``BSON``
   
        - Output the audit events in BSON binary format to the file
          specified in :option:`--auditPath`.
   
   Printing audit events to a file in JSON format degrades server
   performance more than printing to a file in BSON format.
   
   .. include:: /includes/note-audit-in-enterprise-only.rst


.. option:: --auditPath

   .. versionadded:: 2.6
   
   Specifies the output file for :doc:`auditing </core/auditing>` if
   :option:`--auditDestination` has value of ``file``. The :option:`--auditPath`
   option can take either a full path name or a relative path name.
   
   .. include:: /includes/note-audit-in-enterprise-only.rst


.. option:: --auditFilter

   .. versionadded:: 2.6
   
   Specifies the filter to limit the :ref:`types of operations
   <audit-action-details-results>` the :doc:`audit system
   </core/auditing>` records. The option takes a string representation
   of a query document of the form:
   
   .. code-block:: javascript
   
      { <field1>: <expression1>, ... }
   
   The ``<field>`` can be :doc:`any field in the audit message
   </reference/audit-message>`, including fields returned in the
   :ref:`param <audit-action-details-results>` document. The
   ``<expression>`` is a :ref:`query condition expression
   <query-selectors>`.
   
   .. include:: /includes/fact-audit-filter-single-quotes.rst
   
   .. include:: /includes/fact-audit-filter-yaml-configuration.rst
   
   .. include:: /includes/note-audit-in-enterprise-only.rst


SNMP Options
~~~~~~~~~~~~

.. note::

   .. include:: /includes/fact-macos-snmp.rst

.. option:: --snmp-disabled

   
   Disables SNMP access to :binary:`~bin.mongod`. The option is incompatible
   with :option:`--snmp-subagent <mongod --snmp-subagent>` and :option:`--snmp-master <mongod --snmp-master>`.

   .. versionadded:: 4.0.6
   


.. option:: --snmp-subagent

   
   Runs SNMP as a subagent. The option is incompatible with :option:`--snmp-disabled <mongod --snmp-disabled>`.


.. option:: --snmp-master

   
   Runs SNMP as a master. The option is incompatible with :option:`--snmp-disabled <mongod --snmp-disabled>`.


.. seealso::

   - :doc:`/tutorial/monitor-with-snmp`
   - :doc:`/tutorial/monitor-with-snmp-on-windows`
   - :doc:`/tutorial/troubleshoot-snmp`

.. _cli-mongod-inmemory:

inMemory Options
~~~~~~~~~~~~~~~~

.. option:: --inMemorySizeGB <float>

   *Default*: 50% of physical RAM less 1 GB

   .. versionchanged:: 3.4
   
      Values can range from 256MB to 10TB and can be a float.
   
   Maximum amount of memory to allocate for :doc:`in-memory storage
   engine </core/inmemory>` data, including indexes, oplog if the
   :binary:`~bin.mongod` is part of replica set, replica set or sharded
   cluster metadata, etc.
   
   .. include:: /includes/fact-inmemory-storage-engine-default-ram.rst
   
   .. include:: /includes/fact-enterprise-only-admonition.rst
   


.. _encryption-key-management-options:

Encryption Key Management Options
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. option:: --enableEncryption

   *Default*: false

   
   .. versionadded:: 3.2
   
   Enables encryption for the WiredTiger storage engine. This option
   must be enabled in order to pass in encryption keys and
   configurations.
   
   .. include:: /includes/fact-enterprise-only-admonition.rst
   


.. option:: --encryptionCipherMode <string>

   *Default*: AES256-CBC

   
   .. versionadded:: 3.2
   
   The cipher mode to use for encryption at rest:
   
   .. list-table::
      :header-rows: 1
      :widths: 35 65
   
      * - Mode
        - Description
   
      * - ``AES256-CBC``
        - 256-bit Advanced Encryption Standard in Cipher Block Chaining
          Mode
   
      * - ``AES256-GCM``
   
        - 256-bit Advanced Encryption Standard in Galois/Counter Mode
   
          .. versionchanged:: 4.0
   
             .. include:: /includes/fact-aes.rst
   
   .. include:: /includes/fact-enterprise-only-admonition.rst
   


.. option:: --encryptionKeyFile <string>

   
   .. versionadded:: 3.2
   
   The path to the local keyfile when managing keys via process *other
   than* KMIP. Only set when managing keys via process other than KMIP.
   If data is already encrypted using KMIP, MongoDB will throw an error.
   
   Requires :option:`--enableEncryption`.
   
   .. include:: /includes/fact-enterprise-only-admonition.rst
   


.. option:: --kmipKeyIdentifier <string>

   
   .. versionadded:: 3.2
   
   Unique KMIP identifier for an existing key within the KMIP server.
   Include to use the key associated with the identifier as the system
   key. You can only use the setting the first time you enable
   encryption for the :binary:`~bin.mongod` instance. Requires
   :option:`--enableEncryption`.
   
   If unspecified, MongoDB will request that the KMIP server create a
   new key to utilize as the system key.
   
   If the KMIP server cannot locate a key with the specified identifier
   or the data is already encrypted with a key, MongoDB will throw an
   error
   
   .. include:: /includes/fact-enterprise-only-admonition.rst
   


.. option:: --kmipRotateMasterKey <boolean>

   *Default*: false

   
   .. versionadded:: 3.2
   
   If true, rotate the master key and re-encrypt the internal
   keystore.
   
   .. include:: /includes/fact-enterprise-only-admonition.rst
   
   .. seealso:: :ref:`kmip-master-key-rotation`
   


.. option:: --kmipServerName <string>

   
   .. versionadded:: 3.2
   
   Hostname or IP address of the KMIP server to connect to. Requires
   :option:`--enableEncryption`.

   Starting in MongoDB 4.0.14, you can specify multiple KMIP
   servers as a comma-separated list, e.g.
   ``server1.example.com,server2.example.com``. On startup, the
   :binary:`~bin.mongod` will attempt to establish a connection to each
   server in the order listed, and will select the first server to
   which it can successfully establish a connection. KMIP server
   selection occurs only at startup.

   When connecting to a KMIP server, the :binary:`~bin.mongod`
   verifies that the specified :option:`--kmipServerName` matches the
   Subject Alternative Name ``SAN`` (or, if ``SAN`` is not present, the
   Common Name ``CN``) in the certificate presented by the KMIP server.
   If ``SAN`` is present, :binary:`~bin.mongod` does not match against
   the ``CN``. If the hostname does not match the ``SAN`` (or ``CN``),
   the :binary:`~bin.mongod` will fail to connect.

   .. include:: /includes/fact-enterprise-only-admonition.rst
   



.. option:: --kmipPort <number>

   *Default*: 5696

   
   .. versionadded:: 3.2
   
   Port number to use to communicate with the KMIP server.
   Requires :option:`--kmipServerName`. Requires
   :option:`--enableEncryption`.
   
   If specifying multiple KMIP servers with :option:`--kmipServerName`,
   the :binary:`~bin.mongod` will use the port specified with
   :option:`--kmipPort` for all provided KMIP servers.
   
   .. include:: /includes/fact-enterprise-only-admonition.rst
   


.. option:: --kmipClientCertificateSelector <string>

   
   .. versionadded:: 4.0
   
      Available on Windows and macOS as an alternative to
      :option:`--kmipClientCertificateFile`. 
      
      :option:`--kmipClientCertificateFile` and :option:`--kmipClientCertificateSelector` options are mutually exclusive. You can only
      specify one.
   
   Specifies a certificate property in order to select a matching
   certificate from the operating system's certificate store to
   authenticate MongoDB to the KMIP server.
   
   :option:`--kmipClientCertificateSelector` accepts an argument of the format ``<property>=<value>``
   where the property can be one of the following:
   
   .. include:: /includes/extracts/ssl-facts-certificate-selector-properties.rst
   
   .. include:: /includes/fact-enterprise-only-admonition.rst


.. option:: --kmipClientCertificateFile <string>

   
   .. versionadded:: 3.2
   
   String containing the path to the client certificate used for
   authenticating MongoDB to the KMIP server. Requires that a
   :setting:`kmipServerName` be provided.
   
   .. note::
      
      Starting in 4.0, on macOS or Windows, you can use a certificate
      from the operating system's secure store instead of a PEM key
      file. See :option:`--kmipClientCertificateSelector`.
   
   .. include:: /includes/fact-enterprise-only-admonition.rst


.. option:: --kmipClientCertificatePassword <string>

   
   .. versionadded:: 3.2
   
   The password (if one exists) for the client certificate passed into
   :setting:`kmipClientCertificateFile`. Is used for
   authenticating MongoDB to the KMIP server. Requires that a
   :setting:`kmipClientCertificateFile` be provided.
   
   .. include:: /includes/fact-enterprise-only-admonition.rst
   


.. option:: --kmipServerCAFile <string>

   
   .. versionadded:: 3.2
   
   Path to CA File. Used for validating secure client connection to
   KMIP server.
   
   
   .. note::
      
      Starting in 4.0, on macOS or Windows, you can use a certificate
      from the operating system's secure store instead of a PEM key
      file. See :option:`--kmipClientCertificateSelector`. When using the secure store, you do not
      need to, but can, also specify the :option:`--kmipServerCAFile`.