About the Maximum Data Transfer Rate

The firmware suggested default for the A7173A adapter data transfer rate is “MAX” or “NOLIMIT”, which allows a maximum data transfer rate of 320 MB/s. The A7173A can communicate with all LVD or SE devices that have data transfer rates up to 320 MB/s, including the following data transfer rates (synchronous communication over a Wide bus):

The actual data transfer rate between the A7173A adapter and the other SCSI devices on the bus depends on the maximum data transfer rate that is automatically negotiated for each of the devices on the bus.

For example, if you set the A7173A adapter’s maximum data transfer rate to NOLIMIT (which will be 320 MB/s), and then connect a disk drive that has a maximum data transfer rate of Ultra2 (80 MB/s), the actual transfer rate will automatically be negotiated to a maximum of 80 MB/s.

	WARNING! HP DS2100, DS2110, and DS2300 external storage devices are only supported at a maximum SCSI data transfer rate of U160. The SCSI data transfer rate must be limited to U160 (or slower) to avoid potential data integrity issues. The SCSI bus will not automatically adjust to accommodate the DS2100 or the DS2110. The SCSI data transfer rate must be deliberately set to a maximum of U160; offline via the Boot Console Handler (on HP 9000 systems) or EFI (on HP Integrity systems), or online via the mptconfig command. With the DS2300 the SCSI data transfer rate will automatically be negotiated to U160 (or slower), but the negotiation could cause a few SCSI bus resets, which can be avoided by deliberately setting the maximum SCSI data transfer rate to U160.

	TIP: Unless you are connecting an HP DS2100, DS2110, or DS2300 external storage device to an A7173A adapter, HP recommends that you always set the A7173A adapter’s maximum data transfer rate to MAX or NOLIMIT  (this is the default setting for the A7173A adapter). Using MAX or NOLIMIT enables the adapter’s maximum data transfer rate of 320 MB/s to be used, unless there are slower devices on the bus that automatically negotiate a slower data transfer rate. Automatic negotiation of the data transfer rate will set the maximum data transfer rate on the SCSI bus to the maximum data transfer rate capability of the slowest SCSI device on the bus. If you are trying to debug a communication problem between the A7173A adapter and a specific SCSI device, setting the data transfer rate at a slower speed may enhance diagnostic efforts. See Chapter 5: “Troubleshooting”, for more information.

Setting the Maximum Data Transfer Rate Offline

For HP 9000 systems, the Boot Console Handler (BCH) menus are used to set the maximum data transfer rate offline. See “Using the BCH Menus on HP 9000 Systems”, for details.

For HP Integrity® systems, EFI is used to set the maximum data transfer rate offline. See “Using the EFI Utility on HP Integrity Systems”, for details.

Setting the Maximum Data Transfer Rate Online

The mptconfig command is used to set the maximum data transfer rate online for all supported systems. See “Using mptconfig for Online Configuration”, for details.