HP A4800A manual Setting Scsi IDs

IMPORTANT

Installing the A4800A Adapter

Setting SCSI IDs

Setting SCSI IDs

You must assign a separate SCSI ID (0 through 15 for a 16-bit SCSI bus) to the SCSI host bus adapter and each SCSI device. The priority of the device on the SCSI bus is determined by the SCSI ID of the device. The order of SCSI ID priorities (from highest to lowest) is 7, 6, 5, 4, 3, 2, 1, 0, 15, 14, 13, 12, 11, 10, 9, and 8. A device with SCSI ID 7 has the highest priority, and one with SCSI ID 8 has the lowest.

When you are assigning SCSI IDs, we recommend you to give the SCSI host bus adapter higher priority than the other SCSI devices on the bus. SCSI ID 7 is the preset SCSI ID for the A4800A SCSI host bus adapter (giving it the highest priority on the SCSI bus). Set each of the other SCSI devices on the bus to one of the remaining SCSI IDs.

For a multi-initiator (High Availability [HA]) configuration, where multiple SCSI host bus adapters are connected to the same SCSI bus, the SCSI host bus adapter that carries most of the traffic must be assigned a SCSI ID of 7 (giving it the highest priority). Later, you must change the SCSI ID of each of the remaining SCSI host bus adapters on the bus from the preset setting (7) to the next highest priority remaining SCSI IDs (for example, 6, 5, 4, and so on).

If you plan to boot your system from a hard disk drive on the SCSI bus, you must assign that drive the next highest priority unassigned SCSI ID. If there is only one SCSI host bus adapter (SCSI ID = 7), the hard disk drive would be assigned a SCSI ID of 6. If there are multiple SCSI host bus adapters, the hard disk drive would be assigned the next highest priority SCSI ID available after all of the SCSI host bus adapters have been assigned higher priority SCSI IDs.

To change the SCSI ID of the A4800A host bus adapter, refer to “Checking SCSI Bus Compatibility” on page 36.

The peripheral device SCSI IDs are usually set with jumpers or a switch on the peripheral. Refer to the peripheral manufacturer’s instructions to determine the ID of each device and how to change it.

You must not have duplicate SCSI IDs on a SCSI bus; the system will hang or crash if you have duplicate SCSI IDs on the bus.

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