Il 21/01/2013 10:40, Alexandre DERUMIER ha scritto: > Hi list, > > I'm doing some speed benchmark between > > drive-mirror vs qemu-img convert , > > and drive-mirror seem to be a lot slower. > > > test: > > convert 1 32GB qcow2 file to raw file, local storage (6 disk 15k in raid10 + > raid BBU cache) > > time result: > > qemu-img : 30sec > drive-mirror (vm is paused, no writes) : 5min > > > Any idea why drive-mirror is so slow ? (maybe does it use directsync when > mirroring ?)
No, it doesn't. Probably it's because the image is sparse? The current code in git master has a very coarse granularity (1 MB). Please try the blkmirror-job-1.4 branch from my github repo (git://github.com/bonzini/qemu.git). That branch uses the qcow2 file's cluster size as the granularity, and has other optimizations that kick in when the image is sparse. Paolo > I think both should have around same speed ? > > > Best Regards, > > Derumier Alexandre > > >
