On Sun 03/07/11 3:14 PM , Eric Sandeen <sandeen@xxxxxxxxxxx> wrote:
[some rearranging]
> You're welcome but here's the obligatory plug in return - running RHEL5
> proper would have gotten you up to date, fully supported xfs, and you
> wouldn't have run into this mess. Just sayin' ... ;)
Yep, that's definitely a lesson learned. Though I don't think I can blame
CentOS either--from what I can tell the bug has been available from yum for
some time now. So it's pretty much entirely my own fault. :(
I also am sorry for not preserving threading--for some reason, the SGI
mailserver rejected mail from my normal host (which is odd, as it's not in any
blacklists I know of), so I am using an unfamiliar mail client.
> You probably hit this bug:
> http://oss.sgi.com/archives/xfs/2007-01/msg00053.html [1]
>
> See also:
> http://oss.sgi.com/archives/xfs/2009-07/msg00087.html [2]
>
> I can't remember how much damage the original bug did ...
If any? I'm a bit amazed that, if there was damage, that the filesystem is
still usable. Perhaps if I were to fill it it would show signs of
inconsistency? Or remounting would read the now-incorrect values from the
superblock 0?
> is it still mounted I guess?
Yes, it's still mounted, and as far as I can tell perfectly fine. But I won't
really know till I can throw xfs_repair -n and/or xfs_db and/or remount it; I'm
choosing to get as much data off as I can before I try these things, just in
case.
How safe is running xfs_db with -r on my mounted filesystem? I understand that
results might not be consistent, but on the off chance that they are I am
hoping that it might be at least a little helpful.
I was re-reading some of the threads I posted in my original messages, in
particular these posts:
http://oss.sgi.com/archives/xfs/2009-09/msg00210.html
http://oss.sgi.com/archives/xfs/2009-09/msg00211.html
If I am reading those, plus the xfs_db man page, correctly, it seems like what
Russell suggested was to look at superblock 1 (or some other one?) and use
those values to correct superblock 0. At what points (if any) are the other
superblocks updated? I was testing on another machine, on a filesystem that I
had successfully grown using xfs_growfs, and of the two values Russell
suggested the OP to change, dblocks is different between sb 0 and sb 1, but
agcount is not. Could that just be that I did not grow the filesystem too
much, so that agcount didn't need to change? That seems a bit
counterintuitive, but (as should be obvious) I don't know XFS all that well. I
am hoping to know because, in re-reading those messages, I got a better idea of
what those particular xfs_db commands do, so that if I did run into problems
remounting, I might be able to determine the appropriate new values myself and
reduce my downtime. But I want to understand more what I'm doing before I try
that!
--keith
--
kkeller@xxxxxxxxx
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