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Re: [Qemu-devel] [PATCH v3] qemu-img: Implement 'diff' operation.
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v3] qemu-img: Implement 'diff' operation. |
Date: |
Thu, 17 May 2012 09:49:47 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 |
On 05/17/2012 09:34 AM, Richard W.M. Jones wrote:
> From: "Richard W.M. Jones" <address@hidden>
>
> This produces a qcow2 file which is the difference between
> two disk images. ie, if:
>
> base.img - is a disk image (in any format)
> modified.img - is base.img, copied and modified
>
> then:
>
> qemu-img diff -b base.img modified.img diff.qcow2
>
> creates 'diff.qcow2' which contains the differences between 'base.img'
> and 'modified.img'. Note that 'diff.qcow2' has 'base.img' as its
> backing file.
>
> Signed-off-by: Richard W.M. Jones <address@hidden>
> Cc: Matthew Booth <address@hidden>
> Cc: Pablo Iranzo Gómez <address@hidden>
> Cc: Tomas Von Veschler <address@hidden>
Regarding the documentation and command overview:
Reviewed-by: Eric Blake <address@hidden>
Regarding the actual logic used in computing the diff, I did not closely
look at that, and you would be wise to get a review from someone more
familiar with block dev operations.
--
Eric Blake address@hidden +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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