VM backup failing with Err -5

DigitalParadigms

New Member
Jan 2, 2026
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Seeing if anyone has any insight into this issue I am running into:

I am running a single node/non-cluster. ZFS storage. This VM was migrated from VMware recently and was using Veeam which created a successful backup and then decided to start failing. That is when i decided to go ahead and setup the PBS and still ran into issues.

This is the information from the backup failure


INFO: starting new backup job: vzdump 301 --notification-mode notification-system --storage PBS01 --prune-backups 'keep-last=7' --notes-template '{{guestname}}' --fleecing 0 --mode snapshot --quiet 1
INFO: Starting Backup of VM 301 (qemu)
INFO: Backup started at 2026-01-02 01:00:05
INFO: status = running
INFO: VM Name: BDP-Server1.bdp.local
INFO: include disk 'sata2' 'DS-1:vm-301-disk-0' 102432M
INFO: include disk 'sata3' 'DS-1:vm-301-disk-1' 500G
INFO: backup mode: snapshot
INFO: ionice priority: 7
INFO: creating Proxmox Backup Server archive 'vm/301/2026-01-02T06:00:05Z'
INFO: started backup task '6ea05a91-8196-41a1-8c04-9cbce2295436'
INFO: resuming VM again
INFO: sata2: dirty-bitmap status: existing bitmap was invalid and has been cleared
INFO: sata3: dirty-bitmap status: existing bitmap was invalid and has been cleared
INFO: 0% (272.0 MiB of 600.0 GiB) in 3s, read: 90.7 MiB/s, write: 37.3 MiB/s
INFO: 1% (6.0 GiB of 600.0 GiB) in 5m 5s, read: 19.5 MiB/s, write: 17.2 MiB/s
INFO: 1% (7.3 GiB of 600.0 GiB) in 6m 32s, read: 15.7 MiB/s, write: 15.7 MiB/s
ERROR: job failed with err -5 - Input/output error
INFO: aborting backup job
INFO: resuming VM again
ERROR: Backup of VM 301 failed - job failed with err -5 - Input/output error
INFO: Failed at 2026-01-02 01:06:37
INFO: Backup job finished with errors
INFO: notified via target `mail-to-root`
TASK ERROR: job errors
 
Hi,
please check your system logs/journal for any messages around the time of the issue and check the health for the disks underlying the storage DS-1 and the output of zpool status -v.