[Linux-cluster] GFS cluster / DLM locking - Mostly idle but high load

[Wendy Cheng]

Gordan Bobic wrote:

>>>
>>> Yes. The problem doesn't seem to be so bad when files are in different
>>> directories, but when lots of files are being written to the same
>>> directory, the load goes up quite badly.
>>
>>
>> Then this should help. Also enable lock_purging if not already done.
>
>
> That doesn't seem to work for me. :-(
>
> # gfs_tool settune / glock_purge 50
> gfs_tool: can't change tunable parameter glock_purge: Invalid argument
>

I didn't follow this thread of discussion very well. I have to assume 
you're on earlier versions of RHEL 5 ? Newer versions of gfs_kmod should 
have this tunable (can't recall the exact gfs_kmod version it got 
included though).

In general, GFS doesn't perform well when you're writing (and/or 
deleting) large amount of files within one single directory from 
different nodes. This is due to directory lock contention (and directory 
lock needs to get ping-pong between different nodes). We always 
encourage users to avoid this type of setup.

-- Wendy