Poor VMware/RHEL4 SAN performance

[Morten Dalgaard]

Hello there.

In the last couple of days I've been testing SAN performance for VMware ESX 3.0.2 and RHEL 4.

We run HP bl465c blades, with Qlogic QLA2432 HBAs, hooked up to an EVA8000 @ 2gbps.
The RHEL 4 blades runs with the 8.01.06 HP driver, and the VMware ESX server run with the standard driver.

While the Windows blades are able to manage nearly 400Mbytes/sec (with 2 port load balancing), VMware ESX 3.0.2, and RHEL 4 are only able to manage around 80Mbytes/sec. We have this general problem with Linux machines on the SAN.
I suspect the Qlogic Linux driver, however i hear that Emulex cards have the same problem in Linux.
Is it possible to tweak your way out of this with driver options, or is it simply just slower on Linux (why?)

Any suggestions would be greatly appreciated.

[Ted Buis]

VMware creates significant I/O overhead which you are seeing. I don't think you can get around this when using VMware. You might do better with XEN.

[Phillip Thayer]

Don't use the Qlogic Linux driver. Use the HP supplied driver. Also, the Qlogic card you listed is not a mezzanine card. The only mezzanine card for the BL465c is the QMH2462. The drivers for this are at:
http://h20000.www2.hp.com/bizsupport/TechSupport/DriverDownload.jsp?prodNameId=1844105〈=en&cc=us&prodTypeId=329290&prodSeriesId=1844104&taskId=135

It would also be advisable to update all your BIOS and Firmware via VMWare as well. Get these updates at:

http://h18023.www1.hp.com/support/files/server/us/family/model/6310.html

Phil

[Morten Dalgaard]

Thank you for your replies.

In answer to the first reply, that was my thought was well. But after seeing several people on the VMware forums, attain 200Mbyte/sec to 400Mbyte/sec performance with HP blade hardware in a VMware guest OS, i dropped the thought again.

For the second reply - Sorry, i just looked at lspci to find the name which wasn't what was listed there - the HBA is the QMH2462 indeed.
As for drivers, in RHEL we do use the HP drivers. With VMware only the standard VMware driver is supported according to VMware.