Re: xfs corrupted

[Stefanita Rares Dumitrescu <katmai@keptprivate.com>]

another quick update:

after reloading centos 6, i noticed that both arrays were in verifying 
status, so i stopped xfs_repair to see if the raid array has some 
inconsistencies, which it did, and repaired. so my note here is that 
even if the arrays show okay, you should force verify after a power outage.

now the array verify has completed, and some errors were fixed, so i am 
running xfs_repair once more on the broken array.

to keep note, i can now write on the array without issues, lag or whatever.


On 15/10/2013 22:26, Dave Chinner wrote:
> On Tue, Oct 15, 2013 at 09:57:47PM +0200, Stefanita Rares Dumitrescu wrote:
>> Since i am using centos 5.9, the version of the xfsprogs seems to be
>> old, so i cloned the new one from sgi.
>>
>> I have a machine with 4 gb ram, and 4 gb swap, and it's all been
>> eaten up by xfs_repair, and slowed down to a crawl.
>>
>> the sdc partition is the one being checked. i am all out of memory
>> now. 4 gb phys and 4 gb swap all gone.
>>
>> http://pastebin.ca/2467064
>>
>> posted to pastebin for better formatting.
>>
>> i was using:
>>
>> [root@kp4 ~]# xfs_repair -o bhash=16384 -o ihash=16384 -o ag_stride=16 \
>>> /dev/sdc >& /tmp/repair.log
>
> You don't have enough RAM to run threaded prefetching and parallel
> AG processing. You'd do better to turn prefetching off entirely with
> "-P" if you are having OOM problems.
>
>> but now i am trying the -m option to see if the memory can be
>> limited, so the server doesn't freeze.
>>
>> [root@kp4 ~]# xfs_repair -m 3072 -o ag_stride=16 /dev/sdc >& /tmp/repair.log
>>
>> nothing in dmesg either.
>
> Give it another 10-20GB of swap, and it should be fine. xfs_repair
> usually only thrashes swap when you don't have enough of it and it
> keeps trying to free memory, paging in pages that are in swap to
> free cached objects from them. Most of the memory references that
> repair makes are quite local, so when pages are swapped out they
> generally aren't needed again for a while except when cache reclaim
> kicks in. Hence if you give it enough swap that it can grow without
> bounds, then it should still be quite efficient.
>
> Keep in mind that badly corrupted filesystems require lots more
> memory than clean filesystems to check and repair as there is lots
> more intermediate state that repair needs to hold in memory about
> partially or incompletely referenced objects. Don't be surprised if
> the amount of memory needed to repair a badly broken filesystem is
> 10-100x the amount of RAM needed to run xfs_repair on the same clean
> filesystem....
>
> Cheers,
>
> Dave.
>

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