From: Paolo Bonzini <pbonzini@redhat.com>
To: Alexandre DERUMIER <aderumier@odiso.com>
Cc: qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] qmp drive-mirror vs qemu-img convert , drive-mirror really slow
Date: Mon, 21 Jan 2013 11:35:40 +0100 [thread overview]
Message-ID: <50FD19FC.4030209@redhat.com> (raw)
In-Reply-To: <f670b76a-5103-4675-b9cc-2db8c51744ec@mailpro>
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
>
>
>
next prev parent reply other threads:[~2013-01-21 10:35 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <fdc4edd8-3194-4621-a58c-bfee5e5e9826@mailpro>
2013-01-21 9:40 ` [Qemu-devel] qmp drive-mirror vs qemu-img convert , drive-mirror really slow Alexandre DERUMIER
2013-01-21 10:35 ` Paolo Bonzini [this message]
2013-01-21 10:45 ` Alexandre DERUMIER
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