Re: [Qemu-devel] [PATCH 1/3] Add blkmirror block driver

[Stefan Hajnoczi]

On Mon, Feb 27, 2012 at 11:37 AM, Paolo Bonzini <address@hidden> wrote:
> 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.

I'm not familiar with non-incremental mode, could you please explain
it or link to it?

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

That's why I suggested unifying them - take the best of both approaches.

Stefan