VM failing to backup to Proxmox Backup Server, please help

[thetajason]

I have several VMs running on proxmox PVE which are able to automatically backup to a Proxmox backup server with no issues. However, one of the VMs is no longer able to complete a backup and gives the error below. What could be the issue and how can i resolve it?


INFO: 0% (196.0 MiB of 367.0 GiB) in 3s, read: 65.3 MiB/s, write: 25.3 MiB/s
INFO: 1% (3.7 GiB of 367.0 GiB) in 1m 24s, read: 44.6 MiB/s, write: 25.1 MiB/s
INFO: 2% (7.4 GiB of 367.0 GiB) in 2m 42s, read: 48.5 MiB/s, write: 44.1 MiB/s
INFO: 3% (11.1 GiB of 367.0 GiB) in 4m 15s, read: 40.4 MiB/s, write: 29.8 MiB/s
INFO: 4% (14.7 GiB of 367.0 GiB) in 5m 7s, read: 71.1 MiB/s, write: 34.8 MiB/s
INFO: 5% (18.6 GiB of 367.0 GiB) in 5m 31s, read: 167.8 MiB/s, write: 26.5 MiB/s
INFO: 6% (22.4 GiB of 367.0 GiB) in 5m 36s, read: 783.2 MiB/s, write: 1.6 MiB/s
INFO: 7% (26.2 GiB of 367.0 GiB) in 5m 41s, read: 776.0 MiB/s, write: 3.2 MiB/s
INFO: 8% (29.4 GiB of 367.0 GiB) in 5m 45s, read: 807.0 MiB/s, write: 0 B/s
INFO: 8% (32.7 GiB of 367.0 GiB) in 6m 3s, read: 188.9 MiB/s, write: 26.4 MiB/s
ERROR: job failed with err -5 - Input/output error
INFO: aborting backup job
INFO: resuming VM again
ERROR: Backup of VM 110 failed - job failed with err -5 - Input/output error
INFO: Failed at 2025-03-04 14:30:44
INFO: Backup job finished with errors
INFO: notified via target `mail-to-root`
TASK ERROR: job errors

 

[fabian]

that usually means that the source disk is somehow corrupt... please check the system logs during the backup, and provide more details about your setup (hardware, versions, VM config, ..)

 

[thetajason]

im using proxmox 8.2.2
Im running it on an i7 PC with 374 GB on primary drive and 2 TB on a secondary drive. VM storage is on secondary drive using around 370GB as size of its disk.
See attached for VM configuration for the problematic VM.
Other VMs on the same hardware seem to be working and backing up fine

 

[alexskysilk]

ERROR: Backup of VM 110 failed - job failed with err -5 - Input/output error

So this could be a temporary issue relating to bad connectivity (disk channel) OR permanent file corruption.

to check- see if you can do a disk conversion like so:
qemu-img convert -O raw /path/to/vm-110-disk-4.qcow2 /path/to/elsewhere/vm-110-disk-4.raw

Alternatively, make a backup from INSIDE the vm.

IF either of the above works, then you have a good copy of the disk and can now proceed to troubleshoot your sata (or whatever bus the disk is using.)

IF the above fails and you have actual data corruption, you will want to treat it as any other disk corruption- you can use ddrescue or testdisk to recover.