Live backups create-snapshot-as and memspec

[David Wells]

Hi all!

I've been using libvirt for some time and until now I have treated 
backups of virtual computers as if they where physical computers 
installing the backup client on the guest. I am now however facing the 
need to backup a couple a couple of guest at the host level so I've been 
trying to catch up by reading, googling and by trial and error too. Up 
to now I've been able to backup a live machine whith a command like the 
following

> virsh snapshot-create-as --domain test --name backup --atomic 
> --diskspec vda,snapshot=external --disk-only

This command creates a file test.backup and in the meantime I can backup 
the original test.qcow2 but for what I saw this disk image is in a 
"dirty" state, as if the machine I could restore from this file had been 
turned off whithout a proper shutdown.

I know that I can later restore the machine to its original state by 
issuing a command like this

> virsh blockcommit --domain test vda --active --pivot
> virsh snapshot-delete test --metadata backup

I have seen that it is possible to create the snapshot using a memspec 
parameter which would make the backup of the guest as if it where in a 
clean state, however I haven't found the equivalent of the blockcommit 
for the memory file, in a sort of speak, to be able to restore the guest 
to it's original state.

Thank you very much!
Best regards.
David Wells.