General Considerations For Connections - HP Cluster Platform Introduction v2010 Introduction Manual

utilized in the cluster. Other inter-rack cabling considerations also apply, as specified in the
cluster's installation and operation guide.
If you have specific layout requirements for your installation, you must specify the layout at the
time of ordering the system so that the appropriate cable lengths are calculated as part of the
order. Use the information in
a cabling requirements guide. When planning a system layout, computer room cooling is an
important consideration. See

1.6.2 General Considerations for Connections

Using the cable length information from your layout plan, draft a cable routing plan based on
the routing methods used in your computer room. The largest aggregation of cables is where
the cables converge on IBBs and connect to the system interconnect. Your cable layout should
consider the maximum routing capabilities at the IBBs.
Cable Types
Most of the interrack cabling consists of interconnect cables and the type of interconnect
determines which cables are used. Clusters use the following type of cable:
• Proprietary parallel copper (InfiniBand, Quadrics) – These cables have the largest diameter,
and a cable bundle running from one CBB has significant cross-sectional volume. Multiply
the number of connections within a rack by the cable's diameter to calculate the size of
troughs, raceways, and pass-throughs. Cable bundles can cause air dams at cooling ventilation
grilles if not properly routed.
• Ethernet Cat-V or similar serial copper (twisted pair). These cables are used for Gigabit
Ethernet interconnects.
• Fiber-optic cable.
Cable Protection Recommendations
HP recommends that you use troughs or raceways to protect cables. Cable bundle dimensions
for serial copper can preclude the use of open-floor routing or the use of arch protectors unless
the distances are very short — typically a few feet between the racks.
Racks are equipped with suitable strain-relief brackets and hook-and-loop fabric straps. If you
hang cable bundles from raceways, ensure that there is appropriate strain relief and that the
weight of the cable bundle is fully supported by straps or ties.
Ensure that any cable pass-throughs have protective edges so that the cable insulation cannot
be damaged by sharp metal.
Note:
All cables have a recommended minimum bend radius, which affects the way that cables are
routed and how the excess cable lengths can be coiled and stored. Ensure that you factor the
bend radius into your cable length calculations.
Cable Bundle Length
In conjunction with layout planning, ensure that you measure the absolute point-to-point length
of intended cable routes, particularly when constrained by troughs and raceways.
Cable Bundle Dimensions
Interrack connections on multirack clusters are extensive. Be sure to plan adequate space in
troughs, raceways, and pass-throughs.
28 Installation Planning
Section 1.5.1 (page 21)
Section 1.5.4 (page 25).
to draw up a system layout and to generate