On 7/3/11 11:34 PM, kkeller@xxxxxxxxx wrote:
> 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. :(
well it's unfortunate that that kmod persists. I'll admit to providing
it, years and years ago... Centos should find a way to deprecate it...
> 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.
sgi email ... sucks ;)
>> You probably hit this bug:
>> http://oss.sgi.com/archives/xfs/2007-01/msg00053.html 
>> See also: http://oss.sgi.com/archives/xfs/2009-07/msg00087.html
>> 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
it's safe. At worst it might read inconsistent data, but it's
> 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
> I was re-reading some of the threads I posted in my original
> messages, in particular these posts:
> 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
don't worry about correcting anything until you know there is a problem :)
> 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
if you grew it 9T, you would have almost certainly gotten more AGs.
If you did a smaller test then you might see that. To be honest
I don't remember when the backup superblocks get updated.
> 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
I think finding a way to do a dry-run xfs_repair would be the best
place to start ...
Get a recent xfsprogs too, if you haven't already, it scales better
than the really old versions.