Installing Scsi Devices - Compaq AP400 Maintenance And Service Manual

3-38 Removal and Replacement Procedures

Installing SCSI Devices

All workstation models use three areas for connecting mass storage SCSI devices: internally
with hard drive in the removable hard drive cage, internally with storage devices in the front
panel drive bays, and externally with external storage devices. The workstation has an integrated
Wide-Ultra SCSI controller that has one internal connector on the system board and one external
connector on the rear panel.
If you are installing a narrow SCSI device, you will need to attach a 68- to 50-pin SCSI
adapter to the narrow SCSI device.
To preserve data integrity, do not install more than seven SCSI devices per SCSI
controller.
A unique SCSI ID (0-7) must be set for each SCSI device installed. Before you install a
SCSI device, verify the SCSI ID of the drive, and if necessary, set the SCSI ID to a
unique ID number.
The controller identifies a SCSI device by its SCSI ID number rather than its bay location.
Therefore, moving a SCSI device from one bay location to another or changing the
position of the device on the SCSI chain does not affect the communication between the
controller and the SCSI device.
The reserved and available SCSI ID numbers for SCSI devices are as follows:
SCSI ID 0 is reserved for the primary hard drive (bootable drive).
SCSI ID 7 is reserved for the controller.
SCSI IDs 1-6 are available.
Every SCSI chain or circuit must be terminated (closed) at both ends. If using a
terminated cable, disable the termination for all devices. If using a non-terminated cable,
onlydsiable the termination for the last device on the chain.
Turn on an external SCSI device before turning on power to the workstation. This enables
the system board controller to recognize the external SCSI device.
When an external SCSI device is connected to the external SCSI connector on the rear
panel of the workstation, that device becomes the end of the SCSI chain and must be
terminated.
SCSI drives on the SCSI controller must be either internal or in an external storage
system, but not both.
CAUTION: Do not route cables near the air intake to the power supply or the
airflow to the power supply may be blocked, causing overheating.