Storage-logger
==============
The storage-logger project maintains a record of the storage
configuration of a linux system as it changes over time.
The idea is to provide a quick way to check the state
of a system at times in the past.

Logging
=======
The initial logging implementation is triggered by storage uevents and
consists of two components:

1. A new udev rule file, 99-zzz-storage-logger.rules, which runs after
all the other rules have run and invokes:

2. A script, udev_storage_logger.sh, that captures relevant
information about devices that changed and stores it in the system
journal.

The effect is to log relevant uevents plus some supplementary
information.  It does not yet handle filesystem-related events.

Reporting
=========
Two methods to query the data are offered:

1. journalctl
Reports the raw data using simple filtering.
Data is tagged with the identifier UDEVLOG and retrievable as
key-value pairs.
All the captured data:
  journalctl -t UDEVLOG --output verbose
or as JSON:
  journalctl -t UDEVLOG --output json
Between a time range:
  --since 'YYYY-MM-DD HH:MM:SS' 
  --until 'YYYY-MM-DD HH:MM:SS'
Other filtering features are described in the man page.

2. lsblkj
This wrapper creates a dummy system environment that "looks like" the
system did at a specified earlier time and then runs lsblk against it.
It accepts --since and --until arguments to pass to journalctl to
select the desired data, and passes other arguments controlling
the output format to the real lsblk.  
Use --verbose to watch it setting up the temporary environment .
Use --dry-run to see what it would do without actually doing it.
Use --git to create a git repository recording the changes over time.
 
Key Dependencies
================
The logging script requires bash, udev and a systemd journal.
The lsblk wrapper is currently written in perl and requires util-linux
version 2.35 or above and the perl JSON module.

Installation
============
Fedora rawhide packages are available.

Tell the udev daemon to refresh its rules and start logging with
  udevadm control -R

On Fedora, the files get installed into:
  /usr/lib/udev/rules.d/99-zzz-storage-logger.rules
  /usr/sbin/udev_storage_logger.sh
  /usr/bin/lsblkj
  /usr/share/man/man1/lsblkj.1.gz

Feedback
========
Is this useful and should we develop it further?
Please let us know using the linux-lvm mailing list.
  https://www.redhat.com/mailman/listinfo/linux-lvm
  [email protected]