[libvirt-users] Re: managedsave results in unexpected shutdown from inside Windows

The 13/03/13, Eric Blake wrote: I have guests with raw disks due to Windows performance issues. It would very welcome to have minimal downtime as some disks are quiet large (terabytes) and the allowed downtime window very short. Let's try external snapshots for guest "VM" while running: # cd virtuals/images # virsh virsh> snapshot-create-as VM snap1 "snap1 VM" --memspec file=VM.save,snapshot=external --diskspec vda,snapshot=external,file=VM-snap1.img Domain snapshot snap1 created virsh> exit # ls VM-snap1.img ls: cannot access VM-snap1.img: No such file or directory # Ooch! <investigating...> # ls /VM-snap1.img /VM-snap1.img # ls /VM.save /VM.save # Surprising! I would have expect files to be stored in virtuals/images. This is not the point for now, let's continue. # virsh snapshot-list VM Name Creation Time State ------------------------------------------------------------ snap1 2013-03-14 12:20:01 +0100 running # USE CASE 1: restoring from backing file ======================================= # virsh shutdown VM I can't find a snapshot-* doing what I want (snapshot-revert expects to revert a snapshot), trying restore. # virsh restore /VM.save Domain restored from /VM.save # LANG=C virsh snapshot-list VM Name Creation Time State ------------------------------------------------------------ snap1 2013-03-14 12:20:01 +0100 running # As we might expect, the snapshot is still there. # virsh snapshot-delete VM snap1 error: Failed to delete snapshot snap1 error: unsupported configuration: deletion of 1 external disk snapshots not supported yet # A bit annoying. Now, it seems that I have to manually delete garbage. Actually, I've tried and I had to delete /VM.save, /VM-snap1.img, /var/lib/libvirt/qemu/snapshot/VM/snap1.xml and restart libvirt (no snapshot-refresh). USE CASE 2: the files are saved in another place, let's merge back the changes ============================================================================== The idea is to merge VM-snap1.img back to VM.raw with minimal downtime. I can't find a command for that, let's try manually. # virsh managedsave VM # qemu-img commit /VM-snap1.img # rm /VM-snap1.img /VM.save # virsh start VM error: Failed to start domain VM error: cannot open file 'VM-snap1.img': No such file or directory # virsh edit VM <virsh edit VM to come back to vda -> VM.raw> # virsh start VM error: Failed to start domain VM error: cannot open file 'VM-snap1.img': No such file or directory # Looks like the complain comes from the xml state header. # virsh save-image-edit /var/lib/libvirt/qemu/save/VM.save <virsh edit VM to come back to vda -> VM.raw> error: operation failed : new xml too large to fit in file # Stuck. :-/ -- Nicolas Sebrecht