Installing System Options
4–10
Installing Storage Devices
This section covers general drive-installation information, including internal and external
SCSI drives, and cable layouts.
The Digital AlphaStation 255 system supports a maximum of four storage devices
internally. The system comes equipped with one accessible device: a 5.25-inch half-height
removable media device (CD-ROM drive). In addition, you may have up to two
nonaccessible, optional hard drives (two 3.5-inch by 1-inch SCSI disks or one 3.5-inch by
1.6-inch and one 1-inch SCSI disk) within the internal storage bays and a floppy diskette
drive.
Preparing for SCSI Device Installation
To properly prepare for doing a SCSI device installation, you must be familiar with the
available SCSI addresses, SCSI bus length limits, and SCSI termination.
________________________ CAUTION ___________________________
Failure to properly set up the SCSI termination may result in loss of data or
damage to the file system.
____________________________________________________________
SCSI Addresses (SCSI IDs)
Before installing a SCSI drive, you must set the drive's SCSI address (SCSI ID). The SCSI
controller chip is normally assigned SCSI ID 7. Digital recommends that you use the
information in Table 4–1 as a guide for selecting an address for your SCSI drive.
Table 4–1: Selecting a SCSI Address
SCSI Address (ID)
Device (Drive) Recommended
0
System disk (where your operating system resides).
1
Expansion/hard drive.
2
Expansion/hard drive.
3
Expansion.
4
Tape drive (optional).
5
CD-ROM drive.
6
Expansion.
7
Host adapter (SCSI controller).
