Compaq HSZ80 manual Using Preferred ID Numbers

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Using Preferred ID Numbers

Use preferred SCSI target ID numbers to balance the I/O load of storage units among controllers and thereby improve the throughput for the dual-redundant pair of controllers.

You can specify a total of 15 SCSI target ID numbers across both host ports or you can specify 15 SCSI target ID numbers to either Port 1 or Port 2. Use the ID numbers you defined with the SET THIS_CONTROLLER PORT_1_ID (or PORT_2_ID) command.

Enclose multiple IDs in parentheses and separate them by a comma.

In a transparent failover configuration, the other controller automatically inherits the newly defined ID numbers. During normal operation, each controller services only those storage units that are associated with its preferred ID numbers.

You can also use the PREFERRED_ID switch to effectively make the other controller a hot standby by declaring that it has no preferred SCSI target ID numbers. Use the following commands:

SET OTHER_CONTROLLER NOPORT_1_PREFERRED_ID = (n,n)

or

SET OTHER_CONTROLLER NOPORT_2_PREFERRED_ID = (n,n)

By declaring that it has no preferred IDs, this controller will not respond to any SCSI target ID numbers on that port’s host SCSI bus. Instead, the other controller will process all I/O during normal operation.

Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide