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Monitoring your system with Relax-and-Recover

If Relax-and-Recover is not in charge of the backup, but only for creating a rescue environment, it can be useful to know when a change to the system invalidates your existing/stored rescue environment, requiring one to update the rescue environment.

For this, Relax-and-Recover has two different targets, one to create a new baseline (which is automatically done when creating a new rescue environment successfully. And one to verify the (old) baseline to the current situation.

With this, one can monitor or automate generating new rescue environments only when it is really needed.

Creating a baseline

Relax-and-Recover automatically creates a new baseline as soon as it successfully has created a new rescue environment. However if for some reason you want to recreate the baseline manually, use rear savelayout.

Detecting changes to the baseline

When you want to know if the latest rescue environment is still valid, you may want to use the rear checklayout command instead.

[root@system ~]# rear checklayout
[root@system ~]# echo $?

If the layout has changed, the return code will indicate this by a non-zero return code.

[root@system ~]# rear checklayout
[root@system ~]# echo $?

Integration with Nagios and Opsview

If having current DR rescue images is important to your organization, but they cannot be automated (eg. a tape or USB device needs inserting), we provide a Nagios plugin that can send out a notification whenever there is a critical change to the system that requires updating your rescue environment.

Changes to the system requiring an update are:

  • Changes to hardware RAID

  • Changes to software RAID

  • Changes to partitioning

  • Changes to DRBD configuration

  • Changes to LVM

  • Changes to filesystems

The integration is done using our own check_rear plugin for Nagios.

# Purpose: Checks if disaster recovery usb stick is up to date

# Check if ReaR is installed
if [[ ! -x /usr/sbin/rear ]]; then
    exit 2

# ReaR disk layout status can be identical or changed
# returncode: 0 = ok
if ! /usr/sbin/rear checklayout; then
    echo "Disk layout has changed. Please insert Disaster Recovery USB stick into system !"
    exit 2

We also monitor the /var/log/rear/rear-system.log file for ERROR: and BUG BUG BUG strings, so that in case of problems the operator is notified immediately.