Setting Scsi Ids - Adaptec AMM-1510M User Manual

Setting SCSI IDs

Each SCSI device (including the host adapter) located on the SCSI
bus must be set to a unique SCSI ID. The SCSI ID serves two pur-
poses: it uniquely defines each SCSI device's address on the bus, and
it determines the device's priority on the bus during the Arbitration
phase. The Arbitration phase determines which device owns the bus
when two or more devices simultaneously request to use it.
When selecting SCSI IDs, consider the following:
The default value for your host adapter is SCSI ID 7. Normally,
the host adapter should always be set to SCSI ID 7, which is the
ID that has the highest priority on the SCSI bus.
Standard 8-bit SCSI devices can be assigned IDs that range
from 0 to 7; SCSI ID 7 has the highest priority, and SCSI ID 0
has the lowest.
A device's SCSI ID should be changed only if it conflicts with
the SCSI ID of another device or another host adapter (assum-
ing they are on the same SCSI bus).
SCSI IDs play no role in determining the physical order of SCSI
devices cabled to the host adapter.
If you are installing more than one SCSI host adapter, each
adapter implements a different SCSI bus, so SCSI IDs can be
reused.
Changing the SCSI ID setting for the host adapter is software select-
able only and is done through the aspi2dos.sys command line. See
The aspi2dos.sys ASPI Manager in your EZ-SCSI User's Guide for
instructions.
The SCSI ID on most SCSI devices is typically set with jumpers or
with switches on the SCSI device. Refer to the SCSI device documen-
tation for information on changing the SCSI ID on other SCSI
devices.
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AMM-1525M/1510M/525M User's Guide
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Current Date: 9/20/94
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