Virtual SCSI Disk Drive queue_depth

[MoreFeo]

Hi, I've been asked to increase the queue_depth parameter for some virtualized hdisks in a HACMP cluster.

My question is about queue_depth value on the clients and on the VIOs.
If queue_depth is 8 on the VIOs can I set queue_depth to 8 also in the LPARs, or should I set a lower value?

The cluster is formed by 2 LPARs (POWER 6 servers, not sure right now if 550 or 520), double VIO for both LPARs, and the luns are from a HP EVA8400 system.

Rigth now queue depth is 3 on the client LPARs, and 8 on the 4 VIO Servers (double VIO on 2 servers).

Downtime is not a problem, as I also need to change other parameters (aio maxservers) so I will reboot.

Do you have some best practices on the queue_depth values, in VIO environment?

Thanks

 

[MoreFeo]

I've seen in the DS8000 Host attachment redbook that you can set the same queue_depth value for the VIO Servers and the client LPARs, so I suppose there is no problem with setting it to 8 in our client LPARs.

What I've read is that increasing the queue_depth value will reduce the number of luns allowed on a single vscsi adapter, but this will not affect us since we only have 4 luns on these LPARs.