On 11/09/2011 07:35 PM, Anthony Liguori wrote: > On 11/09/2011 11:02 AM, Avi Kivity wrote: >> On 11/09/2011 06:39 PM, Anthony Liguori wrote: >>> >>> Migration with qcow2 is not a supported feature for 1.0. Migration is >>> only supported with raw images using coherent shared storage[1]. >>> >>> [1] NFS is only coherent with close-to-open which right now is not >>> good enough for migration. >> >> Say what? > > Due to block format probing, we read at least the first sector of the > disk during start up. > > Strictly going by what NFS guarantees, since we don't open on the > destination *after* as close on the source, we aren't guaranteed to > see what's written by the source. > > In practice, because of block format probing, unless we're using > cache=none, the first sector can be out of sync with the source on the > destination. If you use cache=none on a Linux client with at least a > Linux NFS server, you should be relatively safe. >
IMO, this should be a release blocker. qemu 1.0 only supporting migration on enterprise storage? If we have to delay the release for a month to get it right, we should. Not that I think we have to. -- error compiling committee.c: too many arguments to function
