Small follow-up on the NBD connections idea, because I asked internally and it turns out that was not a false lead at all. The number of NBD connections is capped per host, so 20 per disk is well past what the host will actually hand out, and it is worth turning down whatever else is going on in this thread. I do not have the exact ceiling yet. I have asked the XAPI side for the real number and I will post it here once I have it, because guessing at it would not help anyone. @Andrew, that fits your side too as far as I can tell, since you are at 1 and have seen this once rather than constantly. probain, I will send you an upload link by direct message so you have somewhere to put the logs. I still do not know whether the fallback itself is new this week or simply newly visible, so please do not read anything into my message on that part.

Yes, you can force start and remove the backup job and that's it.

I removed the start-delay parameter from one of the VMs (only this one has it) and now it works again. I don't get it. No idea how to achieve a startup delay for a specific VM though. There's also "auto_poweron_delay" and I don't understand what the difference from "start-delay" is.

I can't claim to know this part well, but the task name in your screenshot matches an older report, vatesfr/xen-orchestra#7496, where Importing content into VDI XO CloudConfigDrive also sat at 0% forever on XO from sources. In that one the host's self-signed certificate was being refused, and the only visible sign was a DEPTH_ZERO_SELF_SIGNED_CERT line next to importVdiContent in the xo-server log. Nothing showed in the UI at all. Since XOA works for you with the same cloud-config, how each one trusts the host certificate feels like a plausible place to look first, though I could be fully wrong about that. Could you check your xo-server output while one of those tasks is stuck and paste whatever importVdiContent line comes up, along with your commit number? If it reproduces on another host or a fresh build, that would make a solid GitHub issue, and a mention to @Team-XO-Backend might help in the meantime.

@acebmxer all good and thank you again for sharing your discovery on the forums

All hosts are restarted with 9.2.18 loaded now. Will see what happens next. [15:56 ovbh-pprod-xen05 ~]# drbdadm --version DRBDADM_BUILDTAG=GIT-hash:\ 71c8bcff6ea77a022b272a7eba649a774251bac4\ build\ by\ @buildsystem\,\ 2025-11-03\ 10:21:36 DRBDADM_API_VERSION=2 DRBD_KERNEL_VERSION_CODE=0x090212 DRBD_KERNEL_VERSION=9.2.18 DRBDADM_VERSION_CODE=0x092100 DRBDADM_VERSION=9.33.0