[Linux-cluster] GFS Performance Problems (RHEL5)

[Wendy Cheng]

Paul Risenhoover wrote:

>
> Sorry about this mis-send.
>
> I'm guessing my problem has to do with this:
>
> https://www.redhat.com/archives/linux-cluster/2007-October/msg00332.html
>
> BTW: My file system is 13TB.
>
> I found this article that talks about tuning the glock_purge setting:
> http://people.redhat.com/wcheng/Patches/GFS/readme.gfs_glock_trimming.R4
>
> But it seems to require a special kernel module that I don't have :(.  
> Anybody know where I can get it?
>
>

The patch should be part of RHEL 4.6 (or RHEL 5.1) - both will be 
released soon.

-- Wendy

>> Hi All,
>>
>> I am experiencing some substantial performance problems on my RHEL 5 
>> server running GFS.  The specific symptom that I'm seeing is that the 
>> file system will hang for anywhere from 5 to 45 seconds on occasion.  
>> When this happens it stalls all processes that are attempting to 
>> access the file system (ie, "ls -l") such that even a ctrl-break 
>> can't stop it.
>>
>> It also appears that gfs_scand is working extremely hard.  It runs at 
>> 7-10% CPU almost constantly.  I did some research on this and 
>> discovered a discussion about cluster locking in relation to 
>> directories with large numbers of files, and believe it might be 
>> related.  I've got some directories with 5000+ files.  However, I get 
>> the stalling behavior even when nothing is accessing those particular 
>> directories.
>>
>> I also tried some tuning some of the parameters:
>>
>> gfs_tool settune /mnt/promise demote_secs 10
>> gfs_tool settune /mnt/promise scand_secs 2
>> gfs_tool settune /mnt/promise/ reclaim_limit 1000
>>
>> But this doesn't appear to have done much.    Does anybody have some 
>> thoughts on how I might resolve this?
>>
>> Paul
>>
>> -- 
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>
>
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