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Block Based Backup - Insufficient space exists in the volume group

Video - Configuring a block based backup for a LINUX host

NetWorker block based backups are high performance backups which are supported on Windows and Linux only. It has been supported in Windows from a while now but I think the Linux support is from 19.2 onwards only.

Unlike a normal backup During a block based backup the backup application scans a volume or a disk in a file system and backups all the blocks that are in use in the file system. Block based backup uses CBT to keep a track of changed blocks and thus during a subsequent incremental backup only these changed blocks are backed up

Description of the issue

One of the issues that I encountered in my lab setup is that BBB for LINUX failed with an error related to insufficient space being available to complete the backup! But there was enough space on the disk. Taking a closer look at the error it was actually complaining about no free space being available on the volume group to which the partition/mountpoint that I was trying to backup belonged to. Below is the error that I encountered.

Error stack

117677:save: Performing a full backup on saveset '/'.
117678:save: Block based backup shall be performed.
176048:save: Step (6b-i of 7) for PID-6652: Creating the snapshot for the save set '/'.
10/23/21 03:23:13.742713 NsrBlockSave Failed.
174918:save: Step (6 of 7) for PID-6652: Unable to complete the backup. See the savegrp log to track the closure steps of the backup.
117682:save: Block Based Error subsystem error while performing Block Based Backup. Description: 'Insufficient space exists in the volume group 'cl' for creating shadow of the volume /dev/cl/root. Require 1197 MiB but only0 MiB are available.'.
90019:save: save of '/' to server 'nw-linux.crazyrov.com' failed.
142169:save: Save-set ID '4084447328' (client 'linux-1.crazyrov.com': save-set '/') is aborted

Solution

The solution is pretty simple. Below are the steps to add space to the VG that is complaining :

Attach an additional disk to the system that you are trying to backup.
Make sure that the OS can see the attached disk and also get the disk name using the command lsblk
Next format the disk using the command fdisk /dev/disk_name. In the fdisk prompt type n for new partition then p for primary partition, then w
Next confirm that the partition is created successfully using fdisk -l /dev/disk_name. From this point onwards let's assume that the new partition is /dev/sdb1.
You will now need to create a PV on the LVM. For this you use the command pvcreate /dev/sdb1. You can confirm if the PV is created using the pvs.
Now you will have to extend the VG using vgextend cl /dev/sdb1. You can then check the status of the VG using vgs. The output should look similar to below and you should some free space under VFree
Output of the vgs command
```
[root@linux-1 Downloads]# vgs
  VG #PV #LV #SN Attr   VSize  VFree 
  cl   3   2   0 wz--n- 40.99g 16.00g
```

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