@abudef Hi, Do you think this doc can help you? Link to doc I think it needs some improvements, feel free to enhance it if you feel it is necessary!

@florent No explicit assigned migration or backup network set. Backups generate errors somewhat randomly. As one VM won't get the "error" one time. But on the next backup run it will. And the third time it might not. This even happens on VMs that are turned off, and therefore shouldn't have any changed bytes between backups. Host is reachable from XO Network has NBD enabled All VMs use VHD IPv4 Backup type is Delta

@acebmxer we are far more explicit on the real usage of NBD, paing the way to mark a failed NBD connexion as an error in a few month also working on a diagnostic tool to be more efficient on the checks thank you all for your time

@poddingue said: I haven't used that tab myself, and since it's built around VMs that do have backups, I don't know if it gives you the negative view you want. If it doesn't, https://feedback.vates.tech is where that gets counted. Maybe you can build some sort of filter but I don't think so. I'll use https://feedback.vates.tech for future suggestions. Tks

Thanks a lot for this feedback, @pedro!

That should be it, tks @poddingue

Anyone who is using Commvault to back up VMs please tell me what you are using for credintials since you have to connect directly to a pool? I am looking for a way to backup VMs using Commvault and us AD accounts or OIDC.

Thanks for the feedback.

XO 6.7.0 went out on 30 July, and the changelog carries Bastien's fix under Backups as "Fix failed status on successful retry", pointing at PR https://github.com/vatesfr/xen-orchestra/pull/10129 and back at this thread: https://xen-orchestra.com/blog/xen-orchestra-6-7/. Given what you said about keeping the backup XOA on a version you trust, I would not rush it, but that is the version to look for when you do move. I have not exercised the retry path myself, so if a retried VM still reports the job as failed after you upgrade, it is worth saying so here.

So I ended up going with the Windows B&R as i could net setup the windows mount server when setting up the repo for the backups. It would setup the linux one but not the windows one. This was with using the veeam console from a windows client. So i ended up with the Windows one. Now after a few backups i am see this warning / error.... 8/5/2026 5:34:50 PM Warning : Failed to use CBT: [Task e75c4247-2ee1-7b51-088c-b970ace60f3d (Async.VDI.list_changed_blocks) failed: . SR_BACKEND_FAILURE_460. . Failed to calculate changed blocks for given VDIs. [opterr=Source and target VDI are unrelated] First i thought it was because i maped the new job to older backups from Beta v1. So i purged all old backups and started fresh. The full backups were successful. Now on first delta 4 out of 7 vms have that warrning. This a Veeam issue or xcp-ng?

This might have worked, at that time i've allready created new VMs from the information inside the Backup xml file. It worked out allright but building VMs this way, is quite tidious. Maybe there could be a way to find the correct installer and patches, to get a new host in a state to restore a pool backup, would be good.

A remote is not the same thing as a SR. For a remote, it's simple: disconnect it (click on "Enabled" so it's disabled then), do whatever you need on the NFS server, re-enable.

I think this is fixed in 6.7: when a delta backup falls back to a full, the task now shows the actual reason instead of just contradicting itself the way you and Andrew both saw (PR #10148). Worth checking after you upgrade.

Both things reported here look fixed in 6.7: the retry succeeding but the job still showing as failed (PR #10129), and the EEXIST: file already exists error, which happened when a job got recreated after a crash (PR #10139). Curious if upgrading clears it for you all too.

The progress bar issue you and Florent were chasing looks fixed in 6.7 (PR #10133). Worth upgrading and seeing if it moves now instead of sitting still. Separately, since this thread is specifically about QCOW2 backups: 6.7 also fixes an offset bug that could leave incremental backups mostly empty after the first block when NBD isn't enabled. Worth a look at the release notes if that's your setup too.

Good news that it sorted itself out. Both changes went in at once and the next run came back clean on the ADDS VMs too, so I don't think there's anything left to pin down here, and I'd rather say that than invent an explanation after the fact. Your question about the snapshot modes was the useful thing to come out of this thread. I went looking, they genuinely aren't documented anywhere, and that's written up on our side now If the fall back to a full ever comes back on the ADDS VMs specifically, that would deserve its own thread with the SMlog output @tjkreidl asked for, since nobody got to look at that part.

Thanks for the feedback @norpan , worth it! Ping @florent

Got this issue since 2026-07-12.

@pierrebrunet said: Hi, just to be sure, are you saying it is working ok apart one task 8 days ago? Yes, after I adjusted the time it's working