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Re: [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command |
Date: |
Tue, 31 Jul 2012 11:46:54 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 |
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 <address@hidden>
>>
>> [ 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
- [Qemu-devel] [PATCH 42/47] block: allow customizing the granularity of the dirty bitmap, (continued)
- [Qemu-devel] [PATCH 42/47] block: allow customizing the granularity of the dirty bitmap, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 17/47] qemu-iotests: add tests for streaming error handling, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 18/47] block: live snapshot documentation tweaks, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 22/47] block: make device optional in BlockInfo, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 30/47] mirror: implement completion, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command, Paolo Bonzini, 2012/07/24
- Re: [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command, Eric Blake, 2012/07/26
- Re: [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command, Kevin Wolf, 2012/07/31
- Re: [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command, Paolo Bonzini, 2012/07/31
- Re: [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command,
Kevin Wolf <=
- Re: [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command, Paolo Bonzini, 2012/07/31
- Re: [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command, Kevin Wolf, 2012/07/31
- Re: [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command, Paolo Bonzini, 2012/07/31
- Re: [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command, Kevin Wolf, 2012/07/31
- Re: [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command, Paolo Bonzini, 2012/07/31
- Re: [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command, Kevin Wolf, 2012/07/31
- Re: [Qemu-devel] [PATCH 28/47] qmp: add drive-mirror command, Paolo Bonzini, 2012/07/31
[Qemu-devel] [PATCH 21/47] block: add bdrv_ensure_backing_file, Paolo Bonzini, 2012/07/24
[Qemu-devel] [PATCH 35/47] qemu-iotests: add testcases for mirroring on-source-error/on-target-error, Paolo Bonzini, 2012/07/24
[Qemu-devel] [PATCH 24/47] block: introduce new dirty bitmap functionality, Paolo Bonzini, 2012/07/24