When to use the Linux agent's journal exclusions and how to set them

SUMMARY

When to use the Linux agent's journal exclusions and how to set them

ISSUE

Purpose

How to use the Linux agent's journal exclusions in order to minimize journal tracking related load using IBM's ClearCase as an example

Applies To

Linux systems running the Unitrends agent version 6.0.0 and newer

First, check your agent version to see if this KB article applies, ssh to your Linux system and run the command:
cat /usr/bp/bp_VERS

Symptoms / Description

High CPU utilization by /usr/local/bin/mynotify.  This is a process started via the root user's crontab (/var/spool/cron/root, see watchdog).  The daemon monitors the kernel's inotify subsystem for local file system changes.  The daemon monitors these changes minus those specified in /usr/bp/incremental_forever/journal.excludes.  The default entries in this file are:

/var/tmp/

/tmp/

/sys/

/dev/

/usr/bp/

/proc/

 

Cause

If a path in a local file system is highly volatile with changes then mynotify will have to do more work to track all of these changes.  It is essentially seeing each local file system's change in the inotify subsystem.  For each change, it has to compare the item against the exclusion list and conditionally add it to the Unitrends agent's journal.  In many cases, systems such as mail servers, print server, etc., these changes can be taking place within paths that are temporary files that do not need to be backed up and are not required for a disaster recovery event. 

Systems with less processor cores may show a more significant impact due to the journaling of the file system changes.

 

Resolution / Workaround / Execution Process

This has been reported to be an issue for IBM's ClearCase as well.  In this case, the VOB files are being backed up via SAN snapshots, so the files do not need to be backed up from the views of mounted MVFS file systems on the server.  As a result, we made the following changes to address the issue.

!!!  Note:  By adding an item to the journal exclusions, it will _NOT_ be included in differential or incremental backups while /usr/bp/bpinit/master.ini->[Incremental Forever]->UseJournal=true (default if not present).  Items can still be backed up from these paths in master and selective backups, so you may also want to update your exclusion list for the backup to parallel the efforts of your journal exclusion file's content.  This is done in the Unitrends appliance's web interface.

  1. Append each of the following as separate rows to the /usr/bp/incremental_forever/journal.excludes:  /view/, /vob/, etc.
  2. Stop the mynotify daemon by running:  /usr/local/bin/mynotify stop
  3. Confirm the daemon is stopped (no results) by running:  ps -ef | grep mynotify | grep -v grep
  4. Wait for the minute to turn by running the following every 10-15 seconds:  date
  5. Confirm the daemon is started (1 result row) by running:  ps -ef | grep mynotify | grep -v grep
  6. Run a new master backup from the Unitrends appliance web interface

!!!  Note:  If you do choose to disable the journal using /usr/bp/bpinit/master.ini->[Incremental Forever]->UseJournal=true (default if not present), then incremental forever is no longer a valid strategy for this client, AND you no longer need to have mynotify running.  Additionally, you should edit your root user's crontab to either comment or remove the watchdog line, and then run:  /usr/local/bin/mynotify stop

    Third-Party Sources

    n/a

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