Performance Tuning

To get the best performance from the A7173A adapter, HP recommends the following:

Increase the number specified for the maximum queue depth:
- HP-UX 11i v1, 11i v2: The scsi_max_qdepth tunable is dynamic, so no system reboot is needed to change the parameter’s value. See “SCSI Queue Depth Management” in the HP-UX 11i Release Notes for more information about this tunable. If you see “queue full” messages in the /var/adm/syslog.log file, you can avoid those messages by reducing the value for scsi_max_qdepth.
- HP-UX 11i v3: The scsi_max_qdepth tunable has been obsoleted and replaced with the max_q_depth tunable starting with HP-UX 11i v3. The max_q_depth tunable is dynamic, so no system reboot is needed to change the parameter’s value. You can use the scsimgr command to set this value at a global level (such as for all disk devices); for a set of devices (such as for all disk devices from HP); or for a single device (such as for disk0). See the scsimgr (1M) manpage for details.
Install the A7173A adapter in a PCI-X, 133 MHz, 64 bit, 4x (“Twin Turbo” or “Dual Rope”) slot.
Do not connect any Single Ended (SE) SCSI devices on the same SCSI bus with Low Voltage Differential (LVD) SCSI devices. This limits the maximum bus speed to Ultra SCSI (40 MB/s). See “Important Rules For Connecting SCSI Devices”.
When you assign SCSI IDs to SCSI devices on the bus, assign the highest priority SCSI IDs to the devices with the highest volume of data transfer; see “About SCSI IDs”.
Set the A7173A adapter’s maximum data transfer rate to the optimal setting for your configuration; see “About the Maximum Data Transfer Rate”.
Make sure you have the correct SCSI hardware configuration. Domain Validation can detect some configuration problems; see “Domain Validation”.

Performance Tuning

Technical documentation

» Table of Contents

» Glossary

» Index