Scsi-2 (Fast Wide Scsi) External Devices; Table - Sun Microsystems Ultra 30 Reference Manual

2. Determine the total SCSI bus length.

TABLE 1-10

Bus
SCSI Implementation Width
SCSI-2 8 bits
Fast
SCSI-2 16 bits
Fast/Wide
SCSI-3 Parallel 16 bits
Interface,
Fast-20 Wide
(UltraSCSI)
(WideUltra)
SCSI-3 Parallel 16 bits
Interface,
Fast-20 Wide
(UltraSCSI)
(WideUltra)
1. The maximum number of single-ended/differential SCSI devices is 16.
2. The effective internal SCSI bus length of the Ultra 30 system unit is 0.9 meter.
3. Verify the cable type used to connect external SCSI devices.
You must use Fast-20 SCSI cable(s).
4. Ensure that the total SCSI cable length does not exceed the permissible total SCSI
bus length.
A fully-equipped Ultra 30 system with four internal SCSI devices (one CD-ROM
drive, two hard disk drives, one host adapter) enables use of a single 0.8 meter
(32-inch) Fast-20 SCSI cable to a single external SCSI-3 Parallel Interface, Fast-20
Wide (UltraSCSI, WideUltra) device or device cluster.
1.7.4

SCSI-2 (Fast Wide SCSI) External Devices

If you connect SCSI-2 (Fast Wide SCSI, 20 Mbytes data transfer rate) external devices
to a Ultra 30 system, follow these cabling and configuration guidelines to ensure
proper device addressing and operation:
If all external mass storage devices use 68-pin connectors, connect all non-Sun
devices to the Ultra 30 system first and follow them with Sun devices. Sun
devices use autotermination.
Determining SCSI Bus Length
Data Transfer Rate,
Mbytes/s
10
20
40
40
SCSI
Number of Devices Bus Length
1–8 6.0 meters
1–8 6.0 meters
1–4 3.0 meters
1
5–8 1.5 meters
2
2
Chapter -13