24
Hardware Installation and User’s Guide
Hardware Specifications and Features
If both SE and LVD devices are attached to the same channel/bus, the entire bus must
operate at the single ended mode speed of the slower device. See
Table 3-3
for the
maximum cable length distances that apply to each mode.
The preceding information is based on the
‘STA-Endorsed Terms & Terminology for SCSI
Parallel Interface Technology’
specification published by the SCSI Trade Association. It
can be viewed at:
http://www.scsita.org/terms/scsiterms.html
.
Table 3-3. Supported SCSI Device Standards
SCSI Drive
Standard
Bus Speed
(MB/Sec)
Bus Width
(in Bits)
Maximum Cable
Length (meters)
(1)
Maximum Devices
per SCSI Channel
Single-
Ended
LVD
SCSI-1
(2)
5
8
6
(3)
8
Fast SCSI
(2)
10
8
3
(3)
8
Fast Wide SCSI
20
16
3
(3)
16
Ultra SCSI
(2)
20
8
1.5
(3)
8
Ultra SCSI
(2)
20
8
3
N/A
4
Wide Ultra SCSI
40
16
N/A
(3)
16
Wide Ultra SCSI
40
16
1.5
N/A
8
Wide Ultra SCSI
40
16
3
N/A
4
Ultra 2 SCSI
(2, 4)
40
8
(4)
12
8
Wide Ultra 2
(4)
80
16
(4)
12
16
Ultra160 (Ultra 3)
160
16
(4)
12
16
Ultra320
320
16
(4)
12
16
Notes:
(1) May be exceeded in Point-to-Point and engineered specific applications.
(2) Use of the word “Narrow”, preceding SCSI, Ultra SCSI, or Ultra2 SCSI (i.e. Narrow SCSI) is op-
tional.
(3) LVD was not defined in the original SCSI standards for this speed. If all devices on the bus sup-
port LVD, then 12-meters operation is possible at this speed. However, if any device on the bus is
singled-ended only, then the entire bus switches to single-ended mode and the distances in the sin-
gle-ended column apply.
(4) Single-ended is not defined for speeds beyond Ultra.
After Ultra 2 all new speeds are wide only.
