Scsi cabling, Scsi cabling -13 – Avago Technologies eXtremeRAID 3000 User Manual
Page 35
Installation
Manual No. DB11-000033-00
2-13
SCSI Cabling
The controller supports one internal Ultra2 SCSI channel which can support
up to 15 SCSI devices.
LVD Mode
The controller supports Ultra2 SCSI with LVD. If all drives attached to a
controller drive channel support Ultra2 SCSI with LVD, then that channel
will operate at 80MB. This setup allows a maximum SCSI bus length of up
to 12 meters.
☛
Note
The SCSI bus length can be extended up to 25 meters
if only the controller and one drive are on the bus in a
point-to-point configuration.
Single-ended Mode
If any device on the channel does not have LVD electrical characteristics, the
channel will revert to single-ended operation mode. The SCSI bus lengths
will then be limited to the single-ended bus lengths shown in Table 2-2.
* The Maximum number of devices allowed on a Wide Ultra SCSI bus is 8, unless bus
extender technology is used.
† This length can be extended to 25 meters if there are only 2 devices (e.g., the controller and
one drive) on the bus in a point-to-point configuration.
Table 2-2. SCSI Formats and Bus Lengths
SCSI Trade Association
(STA) Terms
Bus
Speed,
MB/Sec,
Max.
Bus
Width,
Bits
Max. Bus Length, Meters
Max. Device
Support
(Including
Controller)
Single-ended
Low-Voltage
Differential
SCSI-1
5
8
6
-
8
Fast SCSI
10
8
3
-
8
Fast Wide SCSI
20
16
3
-
16
Ultra SCSI
20
8
1.5
-
8
Ultra SCSI
20
8
3
-
4
Wide Ultra SCSI
40
16
-
-
16*
Wide Ultra SCSI
40
16
1.5
-
8
Wide Ultra SCSI
40
16
3
-
4
Ultra2 SCSI
40
8
Not Defined
12†
8
Wide Ultra2 SCSI
80
16
Not Defined
12†
16