[Lustre-discuss] High system CPU

[Reto Gantenbein]

Hello Lustre users

We have a Lustre setup consisting of 2 Lustre servers exporting 7 OSTs
and 1 MGS/MDT. The storage devices are FibreChannel-RAIDs connected
through a QLogic SANbox 5602 with the two servers. The servers run the
Lustre-patched 2.6.18 Vanilla sources. We use Lustre 1.6.4.3.

On Client side we have about 180 hosts with Lustre patchless Client and
Gentoo kernel 2.6.22. 

We experienced a major problem when accessing many files at a time.
Especially a `find` does perform very very slowly in our setup. The 4
core MGS/MDT server has nearly 100% system CPU time and the client
nearly the same amount CPU wait time. It's similar when doing a `ls` or
deleting files in a directory with thousands of files.

I did already search though the list, but couldn't find anything
similar.

It seems to me like the MGS/MDT is the bottleneck here, but I have no
idea about tuning it. The MDT storage is a Transtec 4Gbps FibreChannel
SAS Raid. It's configured to use Raid level 1+0.

Does anybody have hints, recommendations, experiences to this topic? 

Kind regards
Reto Gantenbein 


-- 
Universität Bern
Abt. Informatikdienste
Gruppe Zentrale Systeme

Reto Gantenbein
Administrator UBELIX

Gesellschaftsstrasse 6
CH-3012 Bern
Raum -104
Tel.  +41 (0)31 631 87 97