Freeze/thaw VM on Backup

[McShadow]

Hi all,

I'm curious how you handle the 'Freeze/thaw guest filesystems on backup for consistency' option in Qemu Agent.

Do you generally keep it enabled by default? In which scenarios do you explicitly disable it (e.g. high I/O VMs or databases)? Have you had any issues with fsfreeze (timeouts, application impact) or do you consider it safe in most cases?

Has anyone experienced some issues after disabling it?

Thanks,
McShadow

 

[LnxBil]

I don't disable it and never had a problem.

I would, however, add hooks for things like your databases in order to put them properly into backup mode so that the backup is more consistent.

What problems do you see that you want to disable the freeze/thaw?

 

[_gabriel]

keep it for Windows guests, as snapshot is done within guest, like Windows Backup or Veeam done the job.
Disabling is not recommended, because in-use files like databases can't be consistent, except if you shutdown databases engine and close in-use files.

 

[McShadow]

I don't disable it and never had a problem.

I would, however, add hooks for things like your databases in order to put them properly into backup mode so that the backup is more consistent.

What problems do you see that you want to disable the freeze/thaw?

I'm just wondering if there are any reasons for disabling it. Especially when doing backups from high I/O VMs.
How do you handle backups of your databases? What do your hooks do?

keep it for Windows guests, as snapshot is done within guest, like Windows Backup or Veeam done the job.
Disabling is not recommended, because in-use files like databases can't be consistent, except if you shutdown databases engine and close in-use files.

So stun processes haven't been an issue for databases so far?