fsfreeze-hook not called from vzdump snapshot


Renowned Member
Sep 25, 2011
I'm running proxmox-ve: 6.0-2 (running kernel: 5.0.21-5-pve) and as far as I understand "man vzdump"

snapshot mode
This mode provides the lowest operation downtime, at the cost of a small inconsistency risk. It works by performing a Proxmox VE live backup, in which data
blocks are copied while the VM is running. If the guest agent is enabled (agent: 1) and running, it calls guest-fsfreeze-freeze and guest-fsfreeze-thaw to
improve consistency.

should run /etc/qemu/fsfreeze-hook if the qemu-guest-agent is installed and the kvm config contains "agent: 1". A "qm agent 6207 ping" from the proxmox host results in an entry in /var/log/syslog with "qemu-ga: info: guest-ping called". A "qm agent 6207 fsfreeze-freeze" also starts the script /etc/qemu/fsfreeze-hook inside the VM. But the script is not called if I start a backup from the webgui. Any ideas?

INFO: starting new backup job: vzdump 6207 --node xxx --mode snapshot --remove 0 --storage backup-linum --compress lzo
INFO: Starting Backup of VM 6207 (qemu)
INFO: Backup started at 2019-11-27 16:12:26
INFO: status = running
INFO: update VM 6207: -lock backup
INFO: VM Name: xxx
INFO: include disk 'scsi0' 'xxx:vm-6207-disk-0' 32G
INFO: backup mode: snapshot
INFO: ionice priority: 7
INFO: creating archive '/mnt/pve/xxx/dump/vzdump-qemu-6207-2019_11_27-16_12_26.vma.lzo'
INFO: started backup task '8f69cbe1-df7f-4f70-bb37-11c6800d5819'
INFO: status: 2% (748355584/34359738368), sparse 0% (167477248), duration 3, read/write 249/193 MB/s
INFO: status: 100% (34359738368/34359738368), sparse 13% (4512051200), duration 120, read/write 228/224 MB/s
INFO: transferred 34359 MB in 120 seconds (286 MB/s)
INFO: archive file size: 5.62GB
INFO: Finished Backup of VM 6207 (00:08:33)
INFO: Backup finished at 2019-11-27 16:20:59
INFO: Backup job finished successfully
Hmm, strange, just tested with a Debian Buster VM and I see the hook being started in both scenarios, when manually issuing a freeze or when doing a snapshot mode backup...

Which distro is running inside the VM?

What I'll do is adding some logs about the QGA fs freeze/thaw to the backup task, should make it slightly easier to confirm if our code tried to called it.. as now it's pretty silent about that.
Oh sorry, missed the OS inside the VM. It's debian Buster too. But ... the VM was just upgraded from wheezy -> jessie -> stretch -> buster two days before. More log information would be great and I will try to test my scenario with a freshly installed buster VM.


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