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Re: [Qemu-devel] [PATCH V1 1/2] Implement sync modes for drive-backup.
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH V1 1/2] Implement sync modes for drive-backup. |
Date: |
Thu, 04 Jul 2013 09:45:41 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 |
Il 03/07/2013 20:14, Ian Main ha scritto:
>> >
>> > Should the source be "bs" for MIRROR_SYNC_MODE_NONE? Also in this case
>> > you may want to default the format to "qcow2" instead of bs's format.
> I'm not sure that it matters what the source is for NONE. Since we are
> copying all new writes, whether they would go to a top-most layer or not
> shouldn't matter?
It would matter for reads of still-uncopied data, though. You have to
read from the topmost layer, not the one below.
> As for qcow2 format, there is a 'format' option to the drive-backup API
> which specifies the format. I guess we could set the default to qcow2
> instead of the source format? Anyone have any opinions on that?
That would be another possibility. Perhaps use qcow2 for top or none,
and the source format for full.
> I have made the other changes above done. If I don't hear on this issue
> soon I'll post another revision.
You can go ahead and post anyway (just remember to fix the backing file
issue), it is a simple patch on top of what you have.
Paolo