I had the same problems this week on GFS only about 800gig of mostly
small files. My application did not require it to be mounted on the
whole cluster concurrently so i went ahead and switched to EXT3 with
much better performance.
Support said i would probably expect significant improvement with
more RG's but we went with the other file format before we tried that.
Josh
On Oct 27, 2007, at 8:57 AM, Jos Vos wrote:
On Fri, Oct 26, 2007 at 07:57:18PM -0400, Wendy Cheng wrote:
1. 3TB is not "average size". Smaller RG can help with "df" command -
but if your system is congested, it won't help much.
The df also takes ages on an almost idle system. Also, the system
often
needs to do rsyncs on large trees and this takes a very long time too.
In <http://sourceware.org/cluster/faq.html#gfs_tuning> it is suggested
that you should then make the RG larger (i.e. less RGs). As this
requires
shuffling aroung with TB's of data before recreating a GFS fs, I
want to
have some idea of what my chances are that this is usefull.
2. The gfs_scand issue is more to do with the number of glock
count. One
way to tune this is via purge_glock tunable. There is an old write-
up in:
http://people.redhat.com/wcheng/Patches/GFS/
readme.gfs_glock_trimming.R4
. It is for RHEL4 but should work the same way for RHEL5.
I'll try. I assume I can do this per system (so that I don't have to
bring the whole cluster down, only stop the cluster services and
unmount
the GFS volumes per node)?
Any chance this patch will make it into the standard RHEL-package?
I want to avoid to maintain my own patched packages, although as long
as gfs.ko is in the separate kmod-gfs package that's doable.
--
-- Jos Vos <jos@xxxxxx>
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