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[Linux-cluster] GFS 6.0 lt_high_locks value in cluster.ccs

I've been trying to improve the performance of our GFS system since it went live a little over a year ago. Recently, while trying to improve gigabit network performance on another machine that seemed to be having some serious issues, I disabled hyperthreading in the BIOS and performance went through the roof. "Good!" said I. Seeing the performance increase there, I also disabled hyperthreading on two of our main GFS servers providing samba and NFS access to data on GFS filesystems (our backbone is iSCSI over GbE). Performance also generally increased there, but I started to notice two other issues.

Issue #1 is with samba performance: While general access and read/write speeds are much faster now, there are odd delays when trying to copy a file to the filesystem over Samba and when browsing around the filesystem via Samba. The copy to the filesystem delay occurs as soon as the client system (Windows XP) is told to copy a file to the mapped network drive--the window involved will hang for a few seconds, then the copy will start and will move along at a good speed. The delays during browsing happen only occasionally, and don't seem to be related to folder contents.

Issue #2 MAY be the cause of Issue #1. This is hard to determine right now. Issue #2 is that we are now hitting the highwater mark for locks in lock_gulmd almost all day long. This used to happen only occasionally, so we didn't worry about it too much. When it used to happen in the past, it would cause the user experience for Samba users to display the hangs during navigation (though nobody ever mentioned a problem copying files to the system).

So, now to my question: I read on this list in a previous post about the lt_high_locks value in cluster.ccs. Is this a value that can be changed during runtime, or am I going to have to bring all the lock_gulmd's down to change this value?

Jonathan Woytek                 w: 412-681-3463         woytek+ cmu edu
NREC Computing Manager          c: 412-401-1627         KB3HOZ
PGP Key available upon request

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