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

[Stefan Hajnoczi]

On Mon, Aug 20, 2012 at 12:23 PM, Stefan Hajnoczi <address@hidden> wrote:
> On Mon, Aug 20, 2012 at 11:12 AM, Benoît Canet <address@hidden> 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?

Just want to confirm you are thinking about image streaming on top of
quorum?  Or are you thinking about streaming underneath quorum?

Stefan