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[Linux-cluster] GFS Performance Problems (RHEL5)



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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