When running a backup job, I often (but not always) see guests suffer from fatal FS problems. After some point, there will be lines in guest dmesg like `EXT4-fs (sda2): Remounting filesystem read-only` and then the backup does not progress any further. And at this point, the guest needs to rebooted to restore normal operation. And often, fsck finds journal errors that have to be corrected.
Example logs from a backup job:
Example logs from a backup job:
Code:
INFO: VM Name: router
INFO: include disk 'scsi0' 'bootpool:vm-100-disk-1' 32G
INFO: backup mode: snapshot
INFO: ionice priority: 7
INFO: creating Proxmox Backup Server archive 'vm/100/2025-04-23T12:35:08Z'
INFO: enabling encryption
INFO: issuing guest-agent 'fs-freeze' command
INFO: issuing guest-agent 'fs-thaw' command
INFO: started backup task '4ef8f8c6-b113-4e34-b896-536041e669aa'
INFO: resuming VM again
INFO: scsi0: dirty-bitmap status: OK (12.3 GiB of 32.0 GiB dirty)
INFO: using fast incremental mode (dirty-bitmap), 12.3 GiB dirty of 32.0 GiB total
INFO: 3% (488.0 MiB of 12.3 GiB) in 3s, read: 162.7 MiB/s, write: 162.7 MiB/s
INFO: 4% (564.0 MiB of 12.3 GiB) in 6s, read: 25.3 MiB/s, write: 25.3 MiB/s
INFO: 5% (660.0 MiB of 12.3 GiB) in 9s, read: 32.0 MiB/s, write: 32.0 MiB/s
[no further logs, as guest freezes at this point after remounting the fs as read-only]
