Mylex eXtremeRAID 1100, Installation Manual

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2-4 eXtremeRAID Installation Guide
SCSI Cabling
The controller supports up to three Ultra2 SCSI channels. Each channel
supports up to 15 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 80 MB. 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 2-1.
* 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 2-1. Supported 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