DOCS-693 migrate Troubleshooting page

Author: Bob Grabar

source/faq/fundamentals.txt

@@ -222,3 +222,48 @@ operating systems are strongly recommended.
    32-bit builds disable :term:`journaling <journal>` by default
    because journaling further limits the maximum amount of data that
    the database can store.
+
+.. todo Create a Troubleshooting page for these next two faqs on
+   shutdowns and keepalive
+
+The ``mongod`` process has disappeared from the logs. Where can I find information?
+-----------------------------------------------------------------------------------
+
+If :program:`mongod` shuts down unexpectedly on a UNIX or UNIX-based
+platform, and if :program:`mongod` fails to log a shutdown or error
+message, then check the global logs in the ``/var/log/messages``
+directory. Check for messages pertaining to MongoDB by running the
+following commands:
+
+.. code-block:: sh
+
+   sudo grep mongod /var/log/messages
+   sudo grep score /var/log/messages
+
+Does TCP "keepalive" time affect sharded clusters and replica sets?
+-------------------------------------------------------------------
+
+If you are experiencing unexplainable socket errors between members of a
+sharded cluster or replica set, check the ``tcp_keepalive_time`` value.
+The default Linux ``tcp_keepalive_time`` value is ``7200`` seconds (2
+hours). For MongoDB, change this to ``300`` seconds (five minutes).
+
+To check your ``tcp_keepalive_time`` value, issue the following command:
+
+.. code-block:: sh
+
+   cat /proc/sys/net/ipv4/tcp_keepalive_time
+
+To change the ``tcp_keepalive_time`` value, issue the following command:
+
+.. code-block:: sh
+
+   echo 300 > /proc/sys/net/ipv4/tcp_keepalive_time
+
+The new ``tcp_keepalive_time`` value takes effect without requiring you
+to restart not need to restart the :program:`mongod` or
+:program:`mongos` servers.
+
+You must alter the ``tcp_keepalive_time`` value on all machines hosting
+MongoDB processes. This includes all machines hosting :program:`mongos`
+or :program:`mongod` servers.