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xfs_growfs doesn't resize

DISCUSSION [email protected] 2 participants 2 messages Jul 4, 2011

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On Sun 03/07/11 3:14 PM , Eric Sandeen <[email protected]> wrote:

[some rearranging]

Quoted 3 lines

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.

Quoted 7 lines

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?

Quoted 1 line

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

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Quoted 6 lines · On 7/3/11 11:34 PM, [email protected] wrote:

On Sun 03/07/11 3:14 PM , Eric Sandeen <[email protected]> wrote:

[some rearranging]

Quoted 8 lines
Quoted 3 lines

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...

Quoted 4 lines

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 ;)

Quoted 13 lines
Quoted 7 lines

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?

Quoted 8 lines
Quoted 1 line

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 perfectly safe.

Quoted 7 lines

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:

Quoted 6 lines

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

don't worry about correcting anything until you know there is a problem :)

Quoted 7 lines

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.

Quoted 6 lines

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!

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.

-Eric

Quoted 2 lines

--keith

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