On Mon, Mar 19, 2012 at 01:35:19PM +1100, Virgil wrote:
> I'm having a problem with mdraid running in a DomU. The issue is that mdraid
> declares one leg of the raid to have failed (when there's actually nothing
> DomU is fc16 - 3.2.2-1.fc16.x86_64
> Dom0 is fc14 - 188.8.131.52-174.2.xendom0.fc12.x86_64
> The same DomU running on Dom0 fc16 - 3.2.7-1.fc16.x86_64 runs perfectly.
> This appears to be a known issue, however the resolution (which seems to be
> disable barriers on the fly) doesn't seem to work in this case.
hm, that is true - it wouldn't as the workarounds are for filesystems.
But perhaps - is there a way to turn barriers of in the raid system?
> My question is: Is it possible to pass a parameter to the blkfront driver to
> ask it not to enable barrier during initialization? or is there another work
Not that I know of. You could back-port the proper fix to 2.6.32
(or just "Fix" the older 2.6.32 to not advetise feature-barrier).
> [ 1.033058] blkfront: xvda: barrier: enabled
> [ 1.099153] xvda: xvda1 xvda2
> [ 1.102871] blkfront: xvdb: barrier: enabled
> [ 1.130876] xvdb: xvdb1 xvdb2
> [ 1.292692] md: bind<xvdb1>
> [ 1.413416] md: bind<xvda1>
> [ 1.419411] md: raid1 personality registered for level 1
> [ 1.419836] bio: create slab <bio-1> at 1
> [ 1.419953] md/raid1:md127: active with 2 out of 2 mirrors
> [ 1.419992] md127: detected capacity change from 0 to 7516180480
> [ 1.424562] md127: unknown partition table
> [ 1.547284] EXT4-fs (md127): barriers disabled
> [ 1.553107] EXT4-fs (md127): mounted filesystem with ordered data mode.
> Opts: (null)
> [ 1.669483] dracut: Checking ext4: /dev/disk/by-label/rootfs
> [ 1.669592] dracut: issuing e2fsck -a /dev/disk/by-label/rootfs
> [ 1.690595] blkfront: barrier: empty write xvdb op failed
> [ 1.690611] blkfront: xvdb: barrier or flush: disabled
> [ 1.690628] end_request: I/O error, dev xvdb, sector 14682096
> [ 1.690638] end_request: I/O error, dev xvdb, sector 14682096
> [ 1.690646] md: super_written gets error=-5, uptodate=0
> [ 1.690655] md/raid1:md127: Disk failure on xvdb1, disabling device.
> [ 1.690657] md/raid1:md127: Operation continuing on 1 devices.
> [ 1.690677] blkfront: barrier: empty write xvda op failed
> [ 1.690684] blkfront: xvda: barrier or flush: disabled
> [ 1.690696] end_request: I/O error, dev xvda, sector 14682096
> [ 1.690705] end_request: I/O error, dev xvda, sector 14682096
> [ 1.690713] md: super_written gets error=-5, uptodate=0
> [ 1.692991] RAID1 conf printout:
> [ 1.692997] --- wd:1 rd:2
> [ 1.693002] disk 0, wo:0, o:1, dev:xvda1
> [ 1.693006] disk 1, wo:1, o:0, dev:xvdb1
> [ 1.693010] RAID1 conf printout:
> [ 1.693013] --- wd:1 rd:2
> [ 1.693016] disk 0, wo:0, o:1, dev:xvda1
> [ 1.702896] dracut: rootfs: clean, 25635/454272 files, 293967/1835005
> [ 1.703682] dracut: Remounting /dev/disk/by-label/rootfs with -o ro
> [ 1.773347] EXT4-fs (md127): barriers disabled
> [ 1.774552] EXT4-fs (md127): mounted filesystem with ordered data mode.
> Opts: (null)
> [ 1.797159] dracut: Mounted root filesystem /dev/md127
> [ 1.937620] dracut: Switching root
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