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Re: [Qemu-devel] Image streaming and live block copy
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] Image streaming and live block copy |
Date: |
Thu, 16 Jun 2011 15:08:30 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc15 Thunderbird/3.1.10 |
Am 16.06.2011 14:49, schrieb Avi Kivity:
> On 06/16/2011 03:35 PM, Kevin Wolf wrote:
>> * Image streaming is a normal image file plus copy-on-read plus a
>> background task that copies data from the source image
>
> Or a block-mirror started in degraded mode.
At least not in the same configuration as with live block copy: You
don't want to write to the source, you only want to read from it when
the destination doesn't have the data yet.
>> * Live block copy is a block-mirror of two normal image files plus a
>> background task that copies data from the source image
>
> = block-mirror started in degraded mode
>> The right solution is probably to implement COR and the background task
>> in generic block layer code (no reason to restrict it to QED) and use it
>> for both image streaming and live block copy. (This is a bit more
>> complicated than it may sound here because guest writes must always take
>> precedence over a copy - but doing complicated things is an even better
>> reason to do it in a common place instead of duplicating)
>
> Or in a block-mirror block format driver - generic code need not be
> involved.
Might be an option. In this case generic code is only involved with the
stacking of BlockDriverStates, which is already implemented (but
requires -blockdev for a sane way to configure things).
Kevin
- [Qemu-devel] [PATCH 11/13] block: add -drive stream=on|off, (continued)
- [Qemu-devel] [PATCH 11/13] block: add -drive stream=on|off, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 03/13] qed: replace is_write with flags field, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 01/13] qemu-config: }, { -> }, { to please checkpatch.pl, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 02/13] block: add -drive copy-on-read=on|off, Stefan Hajnoczi, 2011/06/14
- Re: [Qemu-devel] [PATCH 00/13] QED image streaming, Philipp Hahn, 2011/06/15
- [Qemu-devel] Image streaming and live block copy (was: [PATCH 00/13] QED image streaming), Kevin Wolf, 2011/06/16
- Re: [Qemu-devel] Image streaming and live block copy, Anthony Liguori, 2011/06/16
- Re: [Qemu-devel] Image streaming and live block copy, Avi Kivity, 2011/06/16
- Re: [Qemu-devel] Image streaming and live block copy,
Kevin Wolf <=
- Re: [Qemu-devel] Image streaming and live block copy, Avi Kivity, 2011/06/16
- Re: [Qemu-devel] Image streaming and live block copy, Marcelo Tosatti, 2011/06/16
- Re: [Qemu-devel] Image streaming and live block copy, Stefan Hajnoczi, 2011/06/16
- Re: [Qemu-devel] Image streaming and live block copy, Marcelo Tosatti, 2011/06/17
- Re: [Qemu-devel] Image streaming and live block copy, Marcelo Tosatti, 2011/06/17
- Re: [Qemu-devel] Image streaming and live block copy, Stefan Hajnoczi, 2011/06/18
- Re: [Qemu-devel] Image streaming and live block copy, Stefan Hajnoczi, 2011/06/18
- Re: [Qemu-devel] Image streaming and live block copy, Dor Laor, 2011/06/19
- Re: [Qemu-devel] Image streaming and live block copy, Stefan Hajnoczi, 2011/06/24
- Re: [Qemu-devel] Image streaming and live block copy, Dor Laor, 2011/06/26