Re: raid5: I lost a XFS file system due to a minor IDE cable problem

[Alberto Alonso <alberto@ggsys.net>]

On Tue, 2007-05-29 at 13:28 +1000, David Chinner wrote:
> On Mon, May 28, 2007 at 05:45:27PM -0500, Alberto Alonso wrote:
> > On Fri, 2007-05-25 at 18:36 +1000, David Chinner wrote:
> > > I consider the possibility of serving out bad data (i.e after
> > > a remount to readonly) to be the worst possible disruption of
> > > service that can happen ;)
> > 
> > I guess it does depend on the nature of the failure. A write failure
> > on block 2000 does not imply corruption of the other 2TB of data.
> 
> The rest might not be corrupted, but if block 2000 is a index of
> some sort (i.e. metadata), you could reference any of that 2TB
> incorrectly and get the wrong data, write to the wrong spot on disk,
> etc.

Forgive my ignorance, but if block 2000 is an index, to access the
data that it references you would go through block 2000, which would
return an error without continuing to access any data pointed to by it.
Isn't that how things work?

> 
> > > > I personally have found the XFS file system to be great for
> > > > my needs (except issues with NFS interaction, where the bug report
> > > > never got answered), but that doesn't mean it can not be improved.
> > > 
> > > Got a pointer?
> > 
> > I can't seem to find it. I'm pretty sure I used bugzilla to report
> > it. I did find the kernel dump file though, so here it is:
> > 
> > Oct  3 15:34:07 localhost kernel: xfs_iget_core: ambiguous vns:
> > vp/0xd1e69c80, invp/0xc989e380
> 
> Oh, I haven't seen any of those problems for quite some time.
> 
> > = /proc/kmsg started.
> > Oct  3 15:51:23 localhost kernel:
> > Inspecting /boot/System.map-2.6.8-2-686-smp
> 
> Oh, well, yes, kernels that old did have that problem. It got fixed
> some time around 2.6.12 or 2.6.13 IIRC....

Time for a kernel upgrade then :-)

Thanks for all your enlightenment, I think I am learning quite a
few things.

Alberto