Re: XFS filesystem corruption

Martin Steigerwald
2013-03-12T09:58:04Z

Am Freitag, 8. März 2013 schrieb Dave Chinner:
> On Thu, Mar 07, 2013 at 02:15:31PM +0100, Julien FERRERO wrote:
> > > We actually test brutal "Power off" for xfs, ext4 and other file
> > > systems. If your storage is configured properly and you have
> > > barriers enabled, they all pass without corruption.
> > >
> > > What hardware raid cards can do is to hide a volatile write cache.
> > > Either on the raid HBA itself or, even worse, on the backend disks
> > > behind the card. S-ata disks tend to default to write cache enabled
> > > and need to be checked especially careful (sas drives tend to be
> > > write cache disabled by default).
> >
> >
> >
> > Write cache is supposed to be disabled on the H/W RAID (according to
> > hdparm) and barrier are correctly enabled since xfs does not report
> > any warning at mount.
> >
> >
> >
> > The odd thing is we never see this with kernel 2.6.18 where barriers
> > weren't yet available.
>
> Yes they were. XFS had barrier support added in 2.6.15.

I thought this was 2.6.16? Or was that the kernel where it became usable due
to the generic write barrier part being merged while the XFS one was ready
earlier?

I still remember the XFS filesystem crashes I had back then that went away
with disabling the write cache of the drive in my ThinkPad T42 back then and
where solved with 2.6.17, whereas 2.6.17.7 solved a directory corruption
issue introduced with 2.6.17. Thus I always recommended at least 2.6.17.7 in
case of write barrier usage with XFS.

Thanks,
--
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
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