Does nofsfreeze: 1 in VMID.conf disable guest-agent fsfreeze during backups in current stable Proxmox?
nofsfreez: 1
- Thread starter Tomek.kapelanski
- Start date
THX!
I would like to clarify the current status of the nofsfreeze: 1 option in VMID.conf.
In the past, some community threads (and unverified documentation snippets) suggested using nofsfreeze: 1 to disable the guest-agent fsfreeze command during VM backup — especially when using PBS with Windows Server + SQL Server guests, to avoid I/O hangs during VSS interaction.
However, the Proxmox GUI now provides an option:
“Freeze/thaw guest filesystems on backup for consistency”
...which writes freeze-fs-on-backup: 0 into the config file.
My questions:
Thank you for clarifying — I want to ensure our backup configurations are both effective and future-proof.
Best regards,
Tomek.kapelanski
I would like to clarify the current status of the nofsfreeze: 1 option in VMID.conf.
In the past, some community threads (and unverified documentation snippets) suggested using nofsfreeze: 1 to disable the guest-agent fsfreeze command during VM backup — especially when using PBS with Windows Server + SQL Server guests, to avoid I/O hangs during VSS interaction.
However, the Proxmox GUI now provides an option:
“Freeze/thaw guest filesystems on backup for consistency”
...which writes freeze-fs-on-backup: 0 into the config file.
My questions:
- Is nofsfreeze: 1 a valid or supported config option in current Proxmox VE versions?
- Should it be removed if freeze-fs-on-backup: 0 is already present?
- Are both equivalent in effect (and do they override each other)?
- Will future versions ignore or deprecate nofsfreeze entirely?
Thank you for clarifying — I want to ensure our backup configurations are both effective and future-proof.
Best regards,
Tomek.kapelanski
Where do you have information about
nofsfreeze from? I would claim, that this option doesn't exist and never did.- as stated already, not valid
- should be removed, because it not a valid option anyway
- nope
- it is already silently ignored, because it is not a valid option.
The original issue with QEMU Agent fsfreeze was that it notified VSS about the backup and all applications subscribed to VSS would prepare for it. In the case of SQL Server, it wrongly understood that it had to trim the log and thus broke the total/incremental/diferential backup chain of SQL Server itself [1]
Nowadays you can simply tell QEMU Agent to notify VSS in a different way so SQL Server doesn't trim logs, etc [2]
[1] https://forum.proxmox.com/threads/p...sql-backups-backups-without-fs-freeze.111526/
[2] https://pve.proxmox.com/wiki/VM_Backup_Consistency