On Wed, Jun 6, 2012 at 3:27 PM, Kevin Wolf <kwolf@xxxxxxxxxx> wrote: > Am 06.06.2012 15:35, schrieb Iain J. Watson: >> Hello, >> >> I am trying to find a way to use backing files to make snapshots of >> running VMs. The idea is I pause the VM, use qemu-img to create a new >> disk file with the currently used file as a backing file, swap the >> images then unpause the VM. >> >> Commands would be something like: >> >> ---------- >> (qemu) stop >> (qemu) drive_del virtio0 >> >> $ qemu-img create -f qcow2 -b os-disk-0.qcow2 os-disk-1.qcow2 >> >> (qemu) drive_add 0 file=os-disk-1.qcow2 # I'm not 100% sure on the >> drive_add syntax >> (qemu) c >> ---------- >> >> If I try and do this just now I get the error "Can't hot-add drive to >> type 7" when running the drive_add command. >> >> Is there another way to achieve this? Is this something that could >> potentially be added or would architecture not support what I'm trying >> to do? > > You're looking for the 'snapshot_blkdev' monitor command: > > (qemu) snapshot_blkdev virtio0 os-disk1.qcow2 qcow2 > > Kevin Ha, it was right in front of my eyes all the time. I thought I'd read that would only do the qcow2 internal snapshot. Guess I was wrong. Quickly trying that throws up an error about not being able to open the new file but I'll debug that a bit before seeking more help. Cheers, Iain -- "Just think how stupid the average person is, and then realize that half of them are even stupider!" --George Carlin -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
