Setting Scsi Ids And Preparing A Boot Device - Adaptec AHA-3980 User Manual

Setting SCSI IDs and Preparing a Boot Device

Each device on the SCSI bus, including the AHA-398x, must have a
unique SCSI ID. SCSI IDs uniquely define each SCSI device on the
bus and determine which device has priority when two or more
devices try to use the SCSI bus at the same time.
SCSI IDs on one channel do not interfere with IDs on another chan-
nel. IDs on one AHA-398x (or channel) do not interfere with those
on other installed adapters (or channels), as long as the adapters (or
channels) implement different SCSI buses.
Allowable SCSI IDs are 0 through 7 for devices on the AHA-3980/
3985. ID 7 has the highest priority, and ID 0 has the lowest. On the
AHA-3980W/3985W, allowable IDs are 0 through 15. The priority of
the remaining IDs, in descending order, is 6 to 0, then 15 to 8.
Setting SCSI IDs is a three-step process:
1
Determine which ID each device on the SCSI bus already has.
The default ID for Channels A, B, and C on the AHA-398x is
ID 7. To determine the IDs of disk drives and other SCSI
devices, read their documentation and examine their switch or
jumper settings.
2
Change the IDs (if needed) so that no two devices on the same
SCSI channel have the same ID. (Leave the channel IDs at the
default of SCSI ID 7.)
If a second AHA-398x or a different SCSI host adapter shares
the same SCSI bus, make sure its ID is not also 7. If necessary,
change either the channel ID or the adapter ID to 6. (See Host
Adapter (Channel) SCSI ID on page 13-2.)
3
If you plan to boot the computer from an array connected to
the AHA-398x adapter, assign SCSI ID 0 to one of the drives
you will use for that array and connect it to channel A. If you
plan to boot the computer from a stand-alone SCSI drive,
assign SCSI ID 0 to that drive. (See Chapter 6, Preparing a Boot
Device and Installing Drivers, for more information.)
If you are installing two or more AHA-398x adapters, be sure
the boot drive or array is connected to the adapter that is
scanned first. See Installing Multiple Adapters on page 5-17 for
more information.
AHA-3980/3980W/3985/3985W User's Guide
Stock Number: 510810-00, Rev. D
Print Spec Number: 493479-00
Current Date: 3/1/99
Installing the AHA-398x and the SCSI Drives
Page: 5-15
ECN Date: 3/19/96
5-15