@dinhngtu Also if it is related to the Rust-based guest agent: do you guys plan to fix the issue and release a new version soon or is it advised to revert to Xenserver guest agent for now?

@akihu2 Perfect, thanks. Yes, you can close this topic

@Pilow Yeah, true. Also during my CBT-enabled-backups tests live migrations did trigger the fallback to a full from time to time aswell (VM residing on a different host during backup run compared to last backup run). But I did those tests ~6 months ago so maybe some fixes have been applied in that regard. You are right, in a thick provision SR / block based scenario taking a snapshot would result in the same size of base VHD being allocated again for the purpose of snapshotting... not really practical. I really hope that CBT receives some more love as we plan to move our storage to a vSAN cluster and intend to use iSCSI instead of NFS by that time so using CBT would also be our best bet then... CBT also reduces the load on the SR (as in I/O) as it removes the need to constantly coalesce disks during backup job re-creation / deletion of snapshots. @acebmxer Interesting during my tests CBT was not really stable as in backups falling back to full quite often. I recall reading somewhere in the documentation that CBT has some quirks so it seems to be a known issue.

Having help from OpenBSD side could be the way to go. Please forward your report to bugs@openbsd.org (with a link to this post too) For the record, I am able to reproduce it too (on XCP-ng 8.3 too, using OpenBSD -current).

@florent Thanks for the reply. I will rebuild XO and test with current master.

patch done by @bastien-nollet

@FritzGerald workaround yum update --exclude=net-snmp*

The update mentioned by Pau should has just been released along with other updates. For more information, you can consult the corresponding blog post: https://xcp-ng.org/blog/2026/03/10/march-2026-maintenance-updates-for-xcp-ng-8-3-lts/