Re: [Qemu-devel] [RFC V3 0/9] Quorum disk image corruption resiliency

[Stefan Hajnoczi <stefanha@gmail.com>]

On Mon, Aug 20, 2012 at 11:12 AM, Benoît Canet <benoit.canet@irqsave.net> wrote:
> Le Tuesday 14 Aug 2012 à 16:14:02 (+0200), Benoît Canet a écrit :
>> This patchset create a block driver implementing a quorum using m qemu disk
>> images. Writes are mirrored on the m files.
>> For the reading part the m files are read at the same time and a vote is
>> done to determine if a qiov version is present n or more times. It then return
>> this majority version to the upper layers.
>> When i < n versions of the data are returned by the lower layer the
>> quorum is broken and the read return -EIO.
>>
>> The goal of this patchset is to be turned in a QEMU block filter living just
>> above raw-*.c and below qcow2/qed when the required infrastructure will be done.
>>
>> Main use of this feature will be people using NFS appliances which can be
>> subjected to bitflip errors.
>>
>> This patchset can be used to replace blkverify and the out of tree blkmirror.
>>
>> usage: -drive file=quorum:n/m:image_1.raw:...:image_m.raw,if=virtio,cache=none
>
> stefanha: I am wondering what would be needed to do in order to have COR and streaming working
> with quorum.c ?

.bdrv_is_allocated()/.bdrv_co_is_allocated() needs to be supported by
block/quorum.c.  Have you tried it and found a problem?

Stefan