HP StorageWorks Clustered File System 3.1.1 for Linux Installation Guide (May 2006)

Chapter 3: Configuration Best Practices 9
QLogic HBA Driver
HP performs all Clustered File System testing with QLogic HBAs
(although Emulex HBAs are also supported). This section provides
insights on interacting with the QLogic driver.
Load Balancing and Failover
The QLogic driver includes a variety of load balancing options. The
8.00.02 driver base only has static load balancing, while the 8.01.xx driver
include several dynamic load balancing schemes. The driver also includes
a failover feature that detects path failures and re-routes I/Os as needed.
The following options control these behaviors. The “modinfo qla2xxx”
command provides a summary of the options. Also see the section
“Setting Driver Options” below:
“ql2xfailover=1”
“ql2xlbType=1”
An alternative approach is to use the mxmpio tool that is part of the HP
Clustered File System. This tool lets you manually tune the load
balancing and failover behavior. This is a much more labor intensive
process than using the capabilities in the driver. However, mxmpio
allows for optimal performance tuning in many environments (contact
your HP Storage expert for performance tuning assistance).
Both this load balancing feature and the failover feature of the driver are
turned off by default.
Multiple Paths and Zoning
The 8.00.02 version of the driver supports a total of eight paths to the
same LUN. The 8.10.xx version supports many more. If more than the
supported number of paths are present, the driver will not correctly deal
with them for load balancing and failover. There are several solutions:
• Turn off failover and load balancing, and manually configure all of
this using the built-in mxmpio tool that is part of HP Clustered File
System.