Re: [libvirt] [RFC]: Snapshot API

On 03/24/2010 04:52 AM, Paolo Bonzini wrote: > >> > How can<parent> be settable? If I have snapshots A and B >> > >> > A -> B -> current state >> > >> > and I create a new snapshot C, then B will be the parent of C. >> > >> > A -> B -> C -> current state >> > >> > If I create another snapshot D now and specify A to be its parent, >> > what's supposed to happen then? >> >> You are right, that doesn't make that much sense. I have to admit that >> the tree structure is the part I thought about least, so I'll take that >> part back. <parent> is just going to be an informational field about >> which snapshot was current (if any) when this one was created. > > If discarding a snapshot also discards the children, it would definitely > make sense to be able to specify the parent. The problem, though, is what Mattias points out; there is no (easy) way that, given state C, I can get back to state A to make a new snapshot. I actually have to be at state A to take a new snapshot with a parent of A. I think this is a place where we have to make it manual; if you really want a new snapshot that is a child of A, you'll have to manually shutdown your domain, boot to snapshot A, then take a snapshot of A.