How to find which chunk is missing in PBS 4.1 after failed verification

[momus]

Hi,

I have strange problem with may oldest backups, some of them had missing chunks (I found 6 snapshots with problems). I have set up verification every 2 days, with skip verified and re-verify after 29 days.

I check logs and I found only this:

2026-03-02T13:57:08+01:00: verify pbs:vm/201/2025-12-07T20:08:29Z
2026-03-02T13:57:08+01:00:   check qemu-server.conf.blob
2026-03-02T13:57:08+01:00:   check drive-scsi0.img.fidx
2026-03-02T15:50:11+01:00:   verified 480789.39/574816.00 MiB in 6782.36 seconds, speed 70.89/84.75 MiB/s (2 errors)
2026-03-02T15:50:11+01:00: verify pbs:vm/201/2025-12-07T20:08:29Z/drive-scsi0.img.fidx failed: chunks could not be verified
2026-03-02T15:50:11+01:00: Failed to verify the following snapshots/groups:
2026-03-02T15:50:11+01:00:     vm/201/2025-12-07T20:08:29Z
2026-03-02T15:50:11+01:00: TASK ERROR: verification failed - please check the log for details

In earlier versions of PBS there was information with which chunk is problem, something like this:

2025-11-21T02:25:50+07:00: can't verify chunk, load failed - store 'MMNAS-BACKUP', unable to load chunk 'b161d0aaac83499fe921ac85a8880e5532f35f7e033df8de38a84b310a4b5bef' - No such file or directory (os error 2)

or there was information that specific chunk has wrong checksum/content.

Now I have only information that there was 2 problem. I have additional backup and I may restore specific chunks from it, but if i don't know which has problem I can do nothing. With one time it helps to create new backup. Because latest snapshot used missing chunk, new backup restored it and it fixed 3 snapshots for that vm that was marked as failed. But now I have situation that this specific chunks are only used in the oldest snapshots.

My PBS is installed in VM i was upgraded in-place from PBS 3. In PBS3 I remember that was information about problematic chunks.
Is there a way in PBS4 to get this information back? or maybe there is in another place, but where?

 

[momus]

Meh, I found this information in systemd logs:

journalctl -u proxmox-backup-proxy.service --since "2026-03-02 12:57:08" --until "2026-03-02 16:50:11"

Then I found:

mar 02 15:50:11 pbs proxmox-backup-proxy[199979]: can't verify chunk, load failed - store 'pbs', unable to load chunk '7101d357ebc172ecc90eae4d3bbdc76bebec3dc5f52a04e27079bb8946376e7f' - No such file or directory (os error 2)
mar 02 15:50:11 pbs proxmox-backup-proxy[199979]: can't verify chunk, load failed - store 'pbs', unable to load chunk 'aefb89538e4f305c94ce42c01648cb5c85a0450874ffd7b03b0af75448c00aa9' - No such file or directory (os error 2)
mar 02 15:50:11 pbs proxmox-backup-proxy[199979]: TASK ERROR: verification failed - please check the log for details

This was earlier in verify log available from PBS.