Setting queue depth with QLogic HBAs

The queue depth is the number of I/O operations that can be run in parallel on a device.

1. Add the following line to the /etc/modules.conf file:

   For the 2.4 kernel (SUSE Linux Enterprise Server 8 or Red Hat Enterprise Linux 3):

   options qla2300 ql2xfailover=0 ql2xmaxqdepth=new_queue_depth

   For the 2.6 kernel (SUSE Linux Enterprise Server 9, or later, or Red Hat Enterprise Linux 4, or later):

   options qla2xxx ql2xfailover=0 ql2xmaxqdepth=new_queue_depth

2. Rebuild the RAM disk that is associated with the kernel being used by using one of the following commands:
   • If you are running on a SUSE Linux Enterprise Server operating system, run the mk_initrd command.
   • If you are running on a Red Hat Enterprise Linux operating system, run the mkinitrd command and then restart.
   Note: Some Linux kernel versions omit the ql2xfailover parameter from the distribution that is provided with the QLogic HBA driver. If this is the case, an error is generated in the /var/log/messages file when booting or loading the qla2xxx module manually. The following error is an example:

   FATAL: Error inserting qla2xxx 
   (/lib/modules/2.6.27.19-5-default/kernel/drivers
   /scsi/qla2xxx/qla2xxx.ko):
   Unknown symbol in module, or unknown parameter

   In these cases, you can omit the ql2xfailover=0 option from the modprobe.conf file, and the module will load correctly.