Am 31.07.2012 11:33, schrieb Paolo Bonzini: > Il 31/07/2012 11:26, Kevin Wolf ha scritto: >> Am 24.07.2012 13:04, schrieb Paolo Bonzini: >>> This adds the monitor commands that start the mirroring job. >>> >>> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> >> >> [ Moving the discussion upstream ] >> >>> Why make all of it inaccessible? Everything except target device access >>> does have a stable API. The target device access can be delayed to 1.3, >>> together with the much-needed QMP schema introspection. >> >> I'm not even sure about the QMP mirror command itself. >> >> I don't really like it, it does too many things at once: It can create >> the target image file, it opens the target and it actually starts the >> mirroring. It's rather bad at the first two steps, because it doesn't >> take any options. This means that it can't create qcow2v3 images, for >> example. Or you can't mirror into a backup with cache=unsafe while >> running your real VM on cache=writethrough. > > Yes, though this can be worked around with mode: 'existing'.
True. Only the problem with image creation, though, not the one with bdrv_open() flags, right? >> Having an all-in-one mirror command is a nice feature for HMP, but for >> QMP it's more like a design problem. >> >> Now I see you have called it drive-mirror > > I thought this was your idea. :) Hm, then probably we discussed similar things before. :-) >> , so that kind of implies that >> it's not the final blockdev-mirror but just a QMP version of a command >> primarily designed for HMP. As such this restricted functionality may be >> acceptable, but it's not like everything is already perfect and there's >> no room for discussion. > > We keep going back to the same point that we do not have -blockdev, but > it's becoming a bit frustrating to always rehash this same point... The question is whether we need it at all. We do have a drive_add if=none, and for creating a mirror target that should actually be enough. Kevin
