Live Snapshot

[Glacier]

Hi 

 

Is it possible to backup a VM (live snapshot)? 

I need to backup up my server vms, but i would rather not be forced to shut them down everyday.

 

/Glacier.

[JorgeB]

It's possible but not recommended since the backup will be in a crash consistent state, you can however do both, e.g., this is what I do, everyday I take a snapshot of all my VMs, including both that are always on, but about once a week, or when I need to stop or reboot unRAID for other reason I take a snapshot with all VMs offline, this way I have more options in case I need to restore from backup.

 

More info here on how to take snapshots and optionally back them up to another disk using btrfs send/receive (btrfs filesystem required):

 

 

 

 

[Dikkekop]

isn't this possible with virsh snapshot ?

 

1. virsh snapshot --domain vm (creates a second vdisk.img and make future writes to this vdisk) (it also points to this vdisk in the .xml file)

2. backup the vm original vdisk.img (no writes take place to this vdisk because of step 1, so "consistent state" ?)

3. virsh blokcommit --domain vm (merge snapshot vdisk to original vdisk, after that deletes the snapshot, and points the orginal vdisk back in .xml)

 

URL of Actual commands: https://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit

 

i'm working/testing on a user script to do this, based on:

 

https://github.com/JTok/unraid-vmbackup

 

Thread:

 

[JorgeB]

AFAIK unless the VM supports it will always be crash consistent, if you snapshot a running VM you won't capture anything currently in RAM.