I/O performance tuning for EVA3000 with rx4640 and qla2300 HBAs

[Doug_95]

What kinds of things can I do to improve my SAN performance from the Host side?

Environment:
rx4640 with 2 1.5MHz Itaniums
16Gig RAM
Oracle RAC 10g (3 nodes, all the same)
RHAS 3, 2.4.21-47.EL
HBAs: qla2300, fw: 3.0.3.11, drv: 7.05.00-f0

I'm considering modifying the hb_qla2x00.conf file.

It looks like this:
qdepth = 16
port_down_retry_count = 3
login_retry_count = 16
failover = 1

How would adjusting the qdepth affect the peformance?

Where else should I be looking?

The application is not moving that much data. In the last 24 hours, the servers are generally in the .5 to 1 MB/s range for a OLTP application. The IOPS generally hang around 300/s total. Mostly reads. A few LUNs get too many writes for a VRAID5. That will be addressed when there is more disk space.

[Ivan Ferreira]

See the following page for additional options:

http://www.redhat.com/magazine/008jun05/features/schedulers/

[Doug_95]

I read that document. It indicated that the default I/O queuing was most likely to be the best. Additionally, I am using AS3 and not four. I know there is a command to tune I/O queuing in AS3, but I really want to know about the effect of Qdepth.