IDE Requirements

An 18-inch long IDE cable that supports two drives is standard in the system. If you install an IDE hard drive, we recommend placing it in the lowest internal drive bay to make cabling easier, particularly if you also have an IDE device in the 5.25-inch drive bay.

For proper IDE operation, note the cable length specified in Figure 15. If no drives are present on an IDE channel, the cable must be removed. If only one drive is installed, it must be connected at the end of the cable.

 

12"

6"

System

Drive 1

Drive 0

board

 

 

18"

Figure 15: IDE Cable DimensionsSCSI Requirements

One wide SCSI cable is standard in the system, connecting the system board to the SCSI backplane.

Terminate only the peripheral at the end of the SCSI cable. Hard drives usually provide active termination, while SCSI CD-ROM drives do not. Because we recommend putting hard drives only in the internal bays, you should route the SCSI cable so that the last device on it is a hard drive in the internal bay. The SCSI backplane in thew internal SCSI drive bay provides active termination for the SCSI drives connected to the backplane.

In general, install legacy devices in the 5.25-inch drive bay and connect them to the narrow SCSI cable. Ultra and Ultra-2 devices are normally hard drives connect them to the SCSI backplane at the rear of the SCSI drive bay. The wide SCSI connectors support either single-ended (SE) or low voltage differential (LVD) drives.

Installing a 5.25-inch Peripheral in the Front Bay

Three 5.25-inch half-height bays provide space for tape backup, CD-ROM, or other removable media drives.

Note:

If you disable the IDE controller to reuse the interrupt for that controller, you must physically unplug the IDE cable from the system board. Simply disabling the drive by configuring the SSU option does not free the interrupt.

Note:

It is important that the cabling and connections meet the SCSI bus specification. Otherwise, the bus may be unreliable and data corruption may occur or devices might not work at all. You must terminate the SCSI bus at the end of the cable; the last device on the cable usually provides bus termination.

Caution!

We recommend that you do not install hard drives in the 5.25-inch bays: the drives cannot be properly cooled in this location; also, a hard drive generates EMI and is therefore more susceptible to ESD in this location.

Installing Hardware 49