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Re: [Qemu-devel] [RFC V3 0/9] Quorum disk image corruption resiliency
From: |
Benoît Canet |
Subject: |
Re: [Qemu-devel] [RFC V3 0/9] Quorum disk image corruption resiliency |
Date: |
Mon, 20 Aug 2012 13:42:08 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Le Monday 20 Aug 2012 à 12:24:33 (+0100), Stefan Hajnoczi a écrit :
> 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?
I am thinking about streaming with quorum on top of a bunch of backing files.
ie: data landing into the higher level backing file living just under quorum.
Benoît
>
> Stefan
- Re: [Qemu-devel] [RFC V3 7/9] quorum: Add quorum_co_flush()., (continued)
- [Qemu-devel] [RFC V3 9/9] quorum: Add quorum mechanism., Benoît Canet, 2012/08/14
- [Qemu-devel] [RFC V3 8/9] quorum: Add quorum_aio_readv., Benoît Canet, 2012/08/14
- Re: [Qemu-devel] [RFC V3 0/9] Quorum disk image corruption resiliency, Blue Swirl, 2012/08/14
- Re: [Qemu-devel] [RFC V3 0/9] Quorum disk image corruption resiliency, Stefan Hajnoczi, 2012/08/15
- Re: [Qemu-devel] [RFC V3 0/9] Quorum disk image corruption resiliency, Benoît Canet, 2012/08/20