HBA load balancing

[MaryJ]

We're using HP Proliant DL 300/500 servers, with HP branded Qlogic HBA cards, that are connected to HP EVAs. We have noticed that most of the luns presented to our hosts, go to Controller A as the preferred path. We'd like to balance this load between controllers. Does HP provide a tool for load balancing? Or would the SANSurfer tool provided by Qlogic work?

Thanks in advance.

[Uwe Zessin]

What EVA and operating system are involved?

On a modern setup with Windows you can make a manual load balancing by setting the 'prefered paths' of the virtual disks on the EVA and then tell the MPIO DSM to enable Adaptive Load Balancing (ALB).

On VMware ESX4, assign your vdisks and then enable RoundRobin.

[Matt Weil]

ql2xlbType=3 should be set on the qlogic driver.

This should keep your luns bouncing from one controller to the other automagicly.

attached is some scripts to help balance luns

use at own risk......

if you access luns between the controllers you are at risk of saturating the link between the controllers (poor performance).

if controller A has a lun and a host is accessing it through controller B...

controller B will access the lun through the connection between the two controllers.

ideally the controller owning the lun is the controller your hosts should be accessing it through.

[MaryJ]

This is a RHEL 4 environment. I checked the settings for ql2xlbType and we have it set to the default (0). We'll try changing it to 3. Thanks!!

[Matt Weil]

2 or 3 should be fine for EVAs