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Date: Mon, 27 Feb 2012 12:37:34 +0100
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Subject: Re: [Qemu-devel] [PATCH 1/3] Add blkmirror block driver
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: kwolf@redhat.com, Federico Simoncelli <fsimonce@redhat.com>, mtosatti@redhat.com, qemu-devel@nongnu.org

On 02/27/2012 10:23 AM, Stefan Hajnoczi wrote:
> > I think the right approach is to create a single blkmirror driver that
> > also includes blkverify functionality.  The code is basically the same
> > except blkverify also compares reads - just use a flag to
> > enable/disable that behavior.
> >
> > Feel free to rename the blkverify driver to blkmirror if you wish.
>
> Federico: Any response to this?  I still think blkmirror and blkverify
> do essentially the same thing and should be unified.

Once non-incremental mode is added, I suspect blkmirror will diverge
from blkverify significantly.  In particular, we would need to track
where have writes been done in the destination.  We also would need to
hooks for block/stream.c, or perhaps a completely separate
implementation of streaming.

Also, blkverify doesn't support cancellation.  I know we do quite poorly
in this area, but I'd rather not make it worse...

Paolo