• Storage Event Notification Daemon
  • Features
  • How-to
  • Event examples
  • FAQ
    • What can be done by kernel
    • Why another daemon?
      • Why not expand udisks for this?
      • Why this tool is better?

Storage Event Notification Daemon

Peripety is designed to parse system storage logging into structured storage event helping user investigate storage issues.

To do so, it provides three tools:

• Daemon -- peripetyd

  The daemon parses incoming storage logs and saved the structured peripety storage event for future query or event notification.

  The daemon has build-in regular expressions for parsing system logs. If that does not works on your system. You may define your own regexs in /etc/peripetyd.conf. Please refer to sample config which contains detail documentation.

• CLI -- prpt

  Command line tool of peripety for event query, event monitor, block information query. Please check manpage of prpr for detail documents.

• Rust binding -- peripety

  Developer friendly interface for query, monitor peripety storage events. Please check crate document for detail. TODO: Add docs.rs link.

Features

• Provides device consistent id, event type and extra information like FC/iSCSI path detail and FS mount point.

• CLI tool prpt to query, monitor events and query block information.

• Non-invasive/non-IO generating for event processing.

• Events are stored in journald with structured data(JSON).

• Allows user defined regex in /etc/peripetyd.conf.

• Rust crate peripety for query block information on all kind of dev string(major:minor, scsi_id, nvme ctrl_id+ns_id, etc).

• TODO: Varlink(JSON) interface.

• TODO: Handle user space tool logs like mulitpathd, iscsid.

How-to

• Install

# Please install systemd-devel package.
make
sudo make install

• Start Daemon

sudo systemctl start peripetyd

• Start monitor CLI

# You may remove the `sudo` if in `systemd-journal` group.
sudo prpt monitor -J

• Trigger some test events

# SCSI sector hardware error
./tests/scsi.sh
# Multipath path failure
./tests/dmmp.sh
# File system I/O error
./tests/fs.sh
# File system over LVM over multipath
./tests/fs_lvm_dmmp.sh
# LVM ThinProvisioning pool full
./tests/lvm_tp.sh

• Query events

# You may remove the `sudo` if in `systemd-journal` group.
sudo prpt query

Event examples

• Ext4 mounted on LVM LV over SCSI multipath

• FC Multipath got path failure

FAQ

What can be done by kernel

I have created some patches hoping kernel could provides in logs:

• Structured log via /dev/kmsg.
• WWID of device matters to fix race issue.
• Event type string to save regex capture.

Why another daemon?

Why not expand udisks for this?

• Current design of udisks require modules written in C which is not a good language for string manipulation which is quit common when parsing eventing.

• Udisks components are trigger by uevent which only have add/change/del event type defined, modules need to extra work to find out what just happened. Yes, we can change udisks to support event types, but IMHO, that require much more work than creating new storage event daemon in rust.

Why this tool is better?

• Rust is almost-memory-leak-proof and quite easy to handle threading, IPC and string manipulation.

• Only do one thing quick and simple -- provide storage events.