Hello,
I'm currently in the process of switching to PBS as backup solution, however I seem to be hitting some kind of bug that causes PBS to hang while backing up a VM. It seems to always happen around the 10 GB mark. Here's the first part of the backup log:
At this point the PBS user interface stops responding. It can be resurrected by issuing the command
The log continues like this then:
PBS is using the S3 backend with the OVH Object Storage. I'm using the newest (no-subscription) packages on both Proxmox and PBS.
The PBS task log doesn't show any errors, last lines are:
Backups to other locations (non-PBS) of this same VM work fine.
I'm currently in the process of switching to PBS as backup solution, however I seem to be hitting some kind of bug that causes PBS to hang while backing up a VM. It seems to always happen around the 10 GB mark. Here's the first part of the backup log:
Code:
INFO: starting new backup job: vzdump 500 --node greystones --notification-mode notification-system --notes-template '{{guestname}}' --remove 0 --storage pbs1 --mode snapshot
INFO: Starting Backup of VM 500 (qemu)
INFO: Backup started at 2026-05-20 11:19:06
INFO: status = running
INFO: VM Name: win10-x
INFO: include disk 'scsi0' 'local-zfs:vm-500-disk-0' 36G
INFO: backup mode: snapshot
INFO: ionice priority: 7
INFO: creating Proxmox Backup Server archive 'vm/500/2026-05-20T09:19:06Z'
INFO: enabling encryption
INFO: issuing guest-agent 'fs-freeze' command
INFO: starting backup via QMP command
INFO: issuing guest-agent 'fs-thaw' command
INFO: started backup task '4845229e-1a03-4603-8585-696bb4b19871'
INFO: resuming VM again
INFO: scsi0: dirty-bitmap status: existing bitmap was invalid and has been cleared
INFO: 1% (372.0 MiB of 36.0 GiB) in 3s, read: 124.0 MiB/s, write: 118.7 MiB/s
INFO: 2% (760.0 MiB of 36.0 GiB) in 9s, read: 64.7 MiB/s, write: 64.7 MiB/s
INFO: 3% (1.1 GiB of 36.0 GiB) in 15s, read: 60.0 MiB/s, write: 60.0 MiB/s
INFO: 4% (1.5 GiB of 36.0 GiB) in 21s, read: 65.3 MiB/s, write: 65.3 MiB/s
INFO: 5% (1.8 GiB of 36.0 GiB) in 28s, read: 48.6 MiB/s, write: 48.6 MiB/s
INFO: 6% (2.2 GiB of 36.0 GiB) in 35s, read: 57.7 MiB/s, write: 57.7 MiB/s
INFO: 7% (2.5 GiB of 36.0 GiB) in 41s, read: 55.3 MiB/s, write: 55.3 MiB/s
INFO: 8% (2.9 GiB of 36.0 GiB) in 48s, read: 58.9 MiB/s, write: 58.3 MiB/s
INFO: 9% (3.3 GiB of 36.0 GiB) in 53s, read: 83.2 MiB/s, write: 83.2 MiB/s
INFO: 10% (3.6 GiB of 36.0 GiB) in 58s, read: 61.6 MiB/s, write: 61.6 MiB/s
INFO: 11% (4.0 GiB of 36.0 GiB) in 1m 4s, read: 58.7 MiB/s, write: 58.7 MiB/s
INFO: 12% (4.3 GiB of 36.0 GiB) in 1m 12s, read: 47.0 MiB/s, write: 47.0 MiB/s
INFO: 13% (4.7 GiB of 36.0 GiB) in 1m 20s, read: 49.5 MiB/s, write: 49.5 MiB/s
INFO: 14% (5.1 GiB of 36.0 GiB) in 1m 27s, read: 48.0 MiB/s, write: 48.0 MiB/s
INFO: 15% (5.4 GiB of 36.0 GiB) in 1m 33s, read: 60.0 MiB/s, write: 60.0 MiB/s
INFO: 16% (5.8 GiB of 36.0 GiB) in 1m 40s, read: 50.9 MiB/s, write: 50.9 MiB/s
INFO: 17% (6.1 GiB of 36.0 GiB) in 1m 47s, read: 54.3 MiB/s, write: 54.3 MiB/s
INFO: 18% (6.5 GiB of 36.0 GiB) in 1m 52s, read: 72.8 MiB/s, write: 72.8 MiB/s
INFO: 19% (6.9 GiB of 36.0 GiB) in 1m 59s, read: 57.1 MiB/s, write: 57.1 MiB/s
INFO: 20% (7.2 GiB of 36.0 GiB) in 2m 6s, read: 49.7 MiB/s, write: 49.7 MiB/s
INFO: 21% (7.6 GiB of 36.0 GiB) in 2m 12s, read: 60.0 MiB/s, write: 59.3 MiB/s
INFO: 22% (7.9 GiB of 36.0 GiB) in 2m 18s, read: 64.0 MiB/s, write: 64.0 MiB/s
INFO: 23% (8.3 GiB of 36.0 GiB) in 2m 25s, read: 57.7 MiB/s, write: 57.7 MiB/s
INFO: 24% (8.7 GiB of 36.0 GiB) in 2m 30s, read: 66.4 MiB/s, write: 66.4 MiB/s
INFO: 25% (9.0 GiB of 36.0 GiB) in 2m 36s, read: 64.7 MiB/s, write: 64.7 MiB/s
INFO: 26% (9.4 GiB of 36.0 GiB) in 2m 42s, read: 60.7 MiB/s, write: 60.7 MiB/s
INFO: 27% (9.7 GiB of 36.0 GiB) in 2m 49s, read: 47.4 MiB/s, write: 47.4 MiB/s
INFO: 28% (10.2 GiB of 36.0 GiB) in 2m 56s, read: 71.4 MiB/s, write: 69.7 MiB/sAt this point the PBS user interface stops responding. It can be resurrected by issuing the command
systemctl restart proxmox-backup-proxy.serviceThe log continues like this then:
Code:
INFO: 28% (10.2 GiB of 36.0 GiB) in 5m 16s, read: 146.3 KiB/s, write: 146.3 KiB/s
ERROR: backup write data failed: command error: protocol canceled
INFO: aborting backup job
INFO: resuming VM again
ERROR: Backup of VM 500 failed - backup write data failed: command error: protocol canceled
INFO: Failed at 2026-05-20 11:24:24
INFO: Backup job finished with errors
INFO: notified via target `mail-to-root`
INFO: notified via target `pushover-x`
TASK ERROR: job errorsPBS is using the S3 backend with the OVH Object Storage. I'm using the newest (no-subscription) packages on both Proxmox and PBS.
The PBS task log doesn't show any errors, last lines are:
Code:
2026-05-20T11:22:05+02:00: Upload new chunk bab7f19c57d4d6127a37d6cc3e4ac986a8fdd2fb1a0922f3f4367746968f9d0d
2026-05-20T11:22:05+02:00: Upload new chunk 6c03478d05d2203285d89c1dcb1847edbe5b15d15f028068c0aeccb76617fc2c
2026-05-20T11:22:05+02:00: Upload new chunk b5f3dc27b4193b07f4632c240b3673a031673834c700b0cb993bb92934eb3312
2026-05-20T11:22:05+02:00: Upload new chunk 60b1a0fb0f59278074ddcc41dabd65025635019e051d878026f39085bb8bd805Backups to other locations (non-PBS) of this same VM work fine.
