NEC EXPRESS800, Service Manual

Page: 31 / 78

Planning Your System Rack Configuration 3-3
RAID Cable Restrictions
RAID Host Adapters use a SCSI cable that connects each Disk Expansion Unit
to its RAID Host Adapter in the Basic System Unit. Cables are available in
3.3-ft (1m) and 9.9-ft (3m) lengths.
Concentrator Cable Lengths
Cables for concentrator connections are available in 7-ft (2.1m) and 12-ft
(3.7m) lengths.
To accommodate the installation of the keyboard, mouse, and monitor on an
external desktop, a 12-ft (3.7m) extension cable that allows you to achieve an
overall cable length of 19-ft (5.8m) or 23-ft (7.3m) is available.
NOTE: Extension cables should only be used between the keyboard, mouse,
and monitor and the concentrator. They cannot be used between the concentrator
and a BSU.
Vertical Spacing
Vertical measurements of rack components are given in Us. 1U is equal to 1.75
inches.
The total usable vertical space within a 42U rack is 42Us or 73.5 inches.
Figure 3-1 illustrates the arrangement of rack mounting holes and their
relationship to a U.