@florent
I disabled CBT on the vms and re-ran a delta backup. I noticed the following.
While watching the backup task when it shows [XO] Exporting it will not show the percentage and completion. Watching backup task a vm will show not using NBD at first but using XO and then fail. The backup log will then show vm fell back to full backup and the task will then show that it is using NBD.
[image: 1776658910502-screenshot_20260420_002103.png]
[image: 1776659182806-screenshot_20260420_002557-resized.png]
[image: 1776659254182-screenshot_20260420_002717.png]
[image: 1776659855936-screenshot_20260420_003717.png]
Also with out CBT GC is not constantly spamming once a vm has finished exporting and started health check. It appears to actually be running and able to coalesce as they are no longer showing in the dashboard / health...
delta job with CBT enabled - 2026-04-20T00_43_48.487Z - backup NG.txt
CBT disabled delta job. two vms fell back to full - 2026-04-20T03_19_02.894Z - backup NG.txt
Next delta job with CBT disabled 1 vm fell back to full - 2026-04-20T04_19_10.531Z - backup NG.txt
[image: 1776658716005-screenshot_20260420_001804-resized.png]
[image: 1776661420315-screenshot_20260420_010236-resized.png]
