[Linux-cluster] slow I/O on v7000 SAN

[Michael Bubb]

Hello -

We are experiencing extreme I/O slowness on a gfs2 volume on a SAN.

We have a:

Netezza TF24
IBM V7000 SAN
IBM Bladecenter with 3 HS22 blades
Stand alone HP DL380 G7 server


The 3 blades and the HP DL380 are clustered using RHEL 6.1 and
clustersuite 5.5.

We have 2 clustered volumes on different storage pools (one has 10k
drives the other 7.2k).

We have an internal test that reads a large file (950G) using fopen and
memmap. On a standalone server in a datacenter (Ubuntu Raid 5 10k disks)
the tests take approximately 75seconds to run.

On the blades the test takes 300 - 350 seconds.

I have been looking at the cluster conf; any gfs tuning I can find. I am
not really sure what I should post here?

yrs

Michael

-- 


Michael Bubb
System Administrator
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