On Thu, Feb 21, 2013 at 06:53:24AM +0000, Dietmar Maurer wrote: > > How would VMA fit in if the backup block job took a BlockDriverState > > destination and vmsave worked atomically with backup block jobs? You could > > have QEMU write to NBD server ports that a VMA writer process has open. > > VMA would happen outside the QEMU process. > > > > The benefit of doing this is that the backup block job becomes a > > general-purpose > > command and QEMU is not directly involved in capturing guest configuration. > > IMO the management tool is the correct place to orchestrate guest restore. > > I am still not sure what you describe here exactly. But this looks like you > want to have > an external backup server (NBD), and move the code out of qemu. > > But NBD is not the only option. There are many backup tool/servers out there, > and > you can easily write a BackupDriver for any of them. Using a fixed protocol > like NBD > does not really have an advantage for me, as you can write a BackupDriver for > that.
I think the reason why Stefan mentioned NBD is that qemu already has an NBD block driver, so if you can backup to a BlockDriverState, you get this for free. However, I don't think there's any reason why we couldn't have a regular (write-only?) VMA block driver inside qemu that can be used for the target BlockDriverState if you want to backup into a VMA. Kevin