Snapshots in Linux VM host?

Nick_C · 07-10-2012, 12:02 PM

Is there any way of taking VM snapshots in KVM/QEmu. I know that there is no snapshot tool built into KVM or anything like that but I seem to recall once reading that there is a way of doing this using Logical Volume Groups or something.

custangro · 07-10-2012, 12:13 PM

If your VM is running on an LVM volume then you should be able to... (Shutdown your VM so you get a quiescent snapshot)

Code:

lvcreate --snapshot vg0/lv_vm --name lv_vm_snapshot --size 512M

Then you can mount that snapshot

Code:

mkdir -m 777 /mnt/lv_vm_snapshot
mount -o ro /dev/vg0/lv_vm_snapshot /mnt/lv_vm_snapshot

Then you can do whatever you want to the /mnt/lv_vm_snapshot dir. Knowing that this is a COW snapshot and you should probably remove it as soon as you're doing doing whatever it is you need to do. Note that the "--size 512M" is the maxsize the snapshot will grow.

-C

dyasny · 07-11-2012, 02:02 AM

if you're not using LVM, you can use qemu-img to take snapshots

Nick_C · 07-23-2012, 11:42 AM

Quote:

Originally Posted by dyasny

if you're not using LVM, you can use qemu-img to take snapshots

Thanks dyasny I didn't know that qemu-img supported snapshots, will try that out.