Compaq HSZ80 manual Unit Number

Table 5–2 Unit Numbering Examples

5–5

■The first character is a letter indicating the kind of device in the storage unit: use D for disk devices or P to indicate passthrough devices such as tape devices, loaders, and libraries.

■If entered, the next one or two digits indicate which target ID number is to access the unit during normal operation. Use one of the controller’s SCSI target ID numbers assigned to the controller with the SET controller ID command. Omit leading zeroes for SCSI target ID numbers less than ten. For example, use 2 instead of 02 for a storageset being accessed through the controller SCSI target ID number 0, LUN 2. The SCSI target ID number is initially set with the SET controller PORT_1_ID (or PORT_2) command. See 5–91for an explanation of the SET controller commands.

By carefully choosing the SCSI target ID number when adding units, the pre- ferred paths for all of your storage units in a dual-redundant configuration can be established. Data I/O load to the units can likewise be controlled by equally dis- tributing unit access between the controllers.

NOTE: When operating in multiple bus failover mode, settings specified with the PORT_1_PREFERRED_ID (or PORT_2) switch takes priority over settings assigned with the SET controller PORT_1_ID (or PORT_2) switch.

■The digit following the SCSI target ID number is always zero.

■The last digit identifies the logical unit number (LUN) for the device or storage unit. Acceptable LUN numbers are 0 through 31, depending on your operating system.

Unit Number	Device Type	Target ID Number	LUN
D1207	disk	12	7
D401	disk	4	1
D39		(not an acceptable unit number)
D5	disk	0	5

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