Windows incremental image backup always uses last full image backup as base

As the title says, the incremental image backup of my windows machine is always based on my last full image backup, which takes a bit of time to complete.
Is this functionality expected?

The server is urbackup 2.4.13 (docker image on ubuntu server).
Client is windows urbackup 2.4.11.

The backups are stored on a BTRFS filesystem.

The online log file does not give much away.

29/04/22 01:02 INFO Starting scheduled incremental image backup of volume C:…
29/04/22 01:02 DEBUG Backing up SYSVOL…
29/04/22 01:02 DEBUG Backing up SYSVOL done.
29/04/22 01:02 DEBUG Backing up EFI System Partition…
29/04/22 01:02 DEBUG Backing up EFI System Partition done.
29/04/22 01:02 INFO Basing image backup on last full image backup

Any info/help is greatly appreciated!
Thank you.


Reading around, it sounds like it is possible to change the functionality, but I’m a little bit confused about which settings I need to change, given that I’m using BTRFS as the backup filesystem.

So, presumably I need to change ‘Local incremental image style’. Is there anything else to change?


Should I also be using raw copy-on-write for the image backup file format?