@christopher-petzel Great news! I will test and report after it is available in a global update. Thank you Christopher.

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?

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

Pour l'ISO montée deux fois : My bad, j'ai ajouter un truc en trop sur mon précédent fix. Une PR est en cours pour corriger ça. Pour le problème principal : J'ai identifié la cause, mais je n'ai pas encore de solution. Sans les drivers Xen (non initialisés avant l'installation), une VM est limitée à 4 périphériques. La séquence de boot ne peut donc pas détecter le second disque contenant le fichier Kickstart (ks). Côté Packer, on semble être bloqués par cette contrainte XCP-ng. Les seules alternatives actuelles seraient de se limiter à : 2 disques + 2 CD ou 3 disques + 1 CD + HTTP (Note : L'installation manuelle fonctionne car l'installateur démarre directement, avec le driver xen_blkfront, alors qu'avec Packer, l'injection de notre fichier interrompt le flux de démarrage classique). Je vais fouiller encore un peu, mais sans certitude d'un contournement possible. (et je regarde pour ajouter le CDlabel)

@andriy.sultanov @andriy.sultanov said: @pandusen As Teddy said above, you can't passthrough a PCI bridge, so there's no PCI devices xapi shouldn't omit here. I am not trying to pass through the bridge only the end points. The Intel arc's have 2 end points: The GPU and the Sound device. "xe pci-list" only reveals the GPU, not the sound device. (this works for nvidia and AMD) But "going the xen-cmdline way" shouldn't break anything, that's what xe pci-disable-dom0-access does behind the scenes. What issues did you see? Which steps did you follow? the sound device is available in the lspci list and can be passed through using CLI. But doing so, (using CLI for passtrough) undoes everything done using xe or the passthrough gui in XO. and results in this: https://xcp-ng.org/forum/topic/10609/xcp-ng-8.3-pci-passthrough-issue so yes, its does break something.

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

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.

@dinhngtu When creating GPOs if you have an non-policy setting for all users in the settings area for the agent config. The policy based registry settings can go into “Software\Policies”, for the appropriate HKEY and keys. In which case the policy based registry entries supersede the non-policy ones, when considering also the HKLM vs HKU and HKCU cascade. Also a disabling of user configuration of the managed setting(s) along with display of a message like “At least some of these settings are managed by the organisation”.

@olivierlambert Happy to hear that they are providing results to be looked at. If there is anything else I can provide, please don't hesitate to ask. And I'll do my very best to be helpfull

Excellent! It's really cool to see how XO Backup and Replication can help you to migrate easily

Got this issue since 2026-07-12.

@acebmxer Thank you for your quick feedback.

Hello @anthoineb, We captured another occurrence on the same VM, os-ott-data-3-2 (172.30.52.193), on the same hypervisor and QCOW2 VDI as the incident reported on 2026-07-25. This occurrence is useful because xen_blkfront.max_ring_page_order=3 was definitely active: xenstore showed ring-page-order=3 with eight ring references; the guest queue depth was 256; 255 write requests remained in flight; all 256 blk-mq scheduler tags were busy; wbt_lat_usec=0; I/O PSI full was approximately 98%; completed xvdb counters did not advance between samples. The backend state was nevertheless the same as in the previous capture: tapdisk was sleeping in scheduler_wait_for_events(); tap-ctl reported reqs_outstanding=0; tap request counters were 0/0; req_prod=0 and rsp_prod=0; no tap, image, VBD, map or xenbus errors were reported. One detail may be relevant: GDB still printed n_reqs=32 and n_reqs_free=32, although the frontend had negotiated an order-3 ring and the guest exposed 256 tags. Is this expected because n_reqs represents a separate fixed tapdisk request pool, or could it indicate that tapdisk is not observing the complete multi-page ring? The controller captured GDB and the guest/hypervisor state before reboot. After the ten-minute diagnostic window, the same signature was confirmed three more times and the VM was rebooted. It rejoined the cluster successfully. I have attached: the complete GDB/tap-ctl capture; the guest blk-mq, diskstats, PSI, D-state stack and kernel-journal snapshot; the corresponding tapdisk/xenstore, daemon.log and SMlog excerpt; a README and SHA-256 checksums. The important new result appears to be that increasing max_ring_page_order from 0 to 3 did not prevent the stall; the same mismatch recurred with 255/256 frontend requests/tags occupied while the backend ring and tapdisk remained empty. 20260730-005220-gdb-172.30.52.193.txt 20260730-pre-reboot-guest-172.30.52.193.txt 20260730-pre-reboot-hypervisor-172.30.50.191.txt README.txt SHA256SUMS.txt

@yannsionneau , may this link helps if you not anyway know it https://medium.com/@timemaster5/getting-amd-phoenix-igpu-passthrough-working-on-xen-xcp-ng-8856593f9c0d I will give it a try this weekend

@MajorP93 Last Message from Veeam: Veeam Support - Case # 08187386 thank you for your email! We are currently waiting for R&D team conclusion, and a bit more time is required for the investigation. I am sorry for the possible inconveniences here! Best regards, Viktoria Nesmiyanova Technical Customer Support - EMEA Veeam Software

@poddingue Fistst of all I appreciate your answer and your position. The thing is that, even though the proxy code itself is opensource, the functionality of the plugin is basicaly behind a paywall. We are not talking about support. Actual functioning of the plugin after compiling from sources depends on license availability and there is no option to select no support or something along the lines "I built it myself from sources". Without patching the code even though the proxy is otherwise functional the backups won't work because of missing license. Hopefully the powers that can will provide an acceptable albeit community supported way to use the proxy cleanly, without touching license checks. Best regards!

I put this on a spare host rather than guess at it twice. The delay runs after the start, not before it. With start-delay=20 the VM was up in about a second and the call then sat there for the rest of the twenty before returning. So the VM you set it on is already running, and what waits is whatever was going to happen next. Ordering does exist, but it belongs to vApps: an appliance groups VMs and order decides which goes first (https://docs.xcp-ng.org/vms/vm-lifecycle#vapps). The part that surprised me is that nothing starts an appliance when the host boots. I put both test VMs in one, rebooted, and they stayed down. Autostart is a single bulk start of everything flagged for auto power on, it walks them one at a time, and it ignores order. I set order=2 on a VM and it still went first. So a delay does hold up the VMs behind it at boot, which is probably what you were seeing, but you cannot pick which one goes first. For your NAS and seedbox I do not think there is a clean answer today. There is an open request for exactly that, a VM that waits on another VM: https://github.com/vatesfr/xen-orchestra/issues/8433, and your case would be a good one to add to it. What I still cannot explain is why yours stopped starting at all. A delay stalling the ones behind it would explain a late start, not one that never comes up.

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.

Then, my earlier suggestion about upgrading was wrong, sorry, better to say so before you spend an evening on it. I went and read the RPU code (it's about time!): shutdownPinnedVms only handles VM_HAS_PCI_ATTACHED, VM_HAS_VGPU and VM_HAS_SRIOV_VIF, and when anything else turns up, it hands back to XAPI's CANNOT_EVACUATE_HOST on purpose. VM_REQUIRES_SR is not in that list, so an upgrade will not move you past it. On the Rolling Pool Update side, the docs say all VM disks have to be on shared storage (https://docs.xcp-ng.org/management/updates), and the host reboot guide defines an agile VM as one not tied to local storage or local devices (https://docs.xcp-ng.org/guides/host-reboot). With everything on local NVMe, that reads to me like RPU is closed to you by design rather than by bug. The route the docs give for your case is the manual one: disable the host, shut the VMs down or migrate them, then reboot. The Smart Reboot message looks like a separate problem. In XO's smartReboot a VM counts as suspend blocked in two different cases, either when blocked_operations.suspend is set, or when XAPI itself refuses VM.assert_operation_valid for suspend. The message only describes the first, which might be why clearing the protection changed nothing. These two will show which one you are in: xe vm-list is-control-domain=false params=name-label,blocked-operations xe vm-list is-control-domain=false power-state=running params=name-label,allowed-operations If suspend is missing from allowed-operations, then XAPI is refusing it rather than a flag you set. I ran both on 8.3, so I know they print something per VM. I have not tested any of this on a two-host pool, though, so the VM_REQUIRES_SR part is my reading of the code rather than something I reproduced.