18 ST12450W/WD Installation Guide, Rev. B
Setting the SCSI ID jumpers
Each device on the SCSI chain must have a unique SCSI
ID. The host system’s SCSI controller usually uses the
highest-numbered ID available (ID15 in wide systems);
therefore the lower-numbered SCSI IDs are normally
used for the other SCSI devices such as this Barracuda
disc drive.
Note.Most SCSI controllers (host adapters) allow you to
skip a SCSI ID. For example, you can have ID0,
ID1, and ID3 (skipping ID2). Other controllers do
not allow this so be sure to refer to your system or
controller user’s manual for details about its re-
quirements for proper SCSI device installation.
Use connector J5 to set the SCSI ID (Figure 2). Most
Barracuda disc drives are factory set with the SCSI ID
set at 0. To change the SCSI ID, install jumpers on the
appropriate pins as shown in the illustration.
If, after completing the installation process, the drive’s
LED does not show on/off activity when the host is trying
to communicate with the drive, a duplicate SCSI ID may
be the problem. If this is the case, change the ID so that
each device on the SCSI chain has its own unique ID.
Also check your system or controller user’s manual to
ensure that you have not violated its SCSI ID numbering
recommendations.