PC Hardware in a Nutshell, 3rd Edition

Installing a SCSI Hard Disk

When installing and configuring a SCSI hard disk, use the following guidelines:

• If possible, avoid mixing different types of SCSI devices on the same bus. For example, if your system has an Ultra160 SCSI hard disk and Ultra-SCSI CD-ROM, CD-RW, and tape drives installed, put the fast hard disk on its own SCSI bus and install the slower SCSI devices on a separate SCSI bus. If necessary, purchase and install an inexpensive SCSI host adapter to support the slower devices.

• For easiest installation and configuration, use all SCAM-compliant devices. SCAM-compliant drives allow a SCAM-compliant host adapter to set the drive’s SCSI ID and termination status automatically. SCAM-tolerant drives report their SCSI ID and termination status to the adapter, but you must manually change settings on the drive if SCSI ID and/or termination need to be altered. Non-SCAM drives neither report their current settings to the adapter nor allow the adapter to reset them automatically. When using non-SCAM devices, you must manually verify settings and change them as necessary.

• Many SCSI problems are cable-related. The cables supplied with SCSI hard disks and host adapters are usually of decent quality, but we’ve seen some truly horrible ones. Good SCSI cables aren’t cheap, and the $3 ones you find in the bin at computer stores should be avoided. We’ve always found Adaptec SCSI cables to be both reasonably priced and of high quality.

Tip

If you plan to boot the system from a SCSI hard ...