Intel SGI Altix 450 manual Determining Where to Attach Rails in a Rack

Installing the IRUs in a Rack

Determining Where to Attach Rails in a Rack

The base IRU, and any additional IRUs, each require five units (5U) of vertical space within the rack (one unit is equivalent to 1.75 inches [44.5 mm]). To determine where you should install the unit’s shelf rails in the rack, you must count mounting holes. Each U contains three mounting holes; therefore, in the 5U of space that the module occupies, there are 15 mounting holes. The bottom hole of the 5U space is hole 1. The top mounting hole in the 5U space is hole 15. See Figure 1-11.

Note: An IRU in the rack is identified by the lowest U number that it occupies. For example, in Figure 1-11 the IRU’s bottom is in U1 (the first unit within the rack).

16th hole

Figure 1-11

8	8
7	7
6	6
5	5
4	4
3	3
2	2
1	1

Mounting Hole Pattern of Rack Rails

5U

To determine how many mounting holes you must count, use the following formula: 3 x (the lowest U number that the module will occupy) - 2. For example, when you want to install the module in locations U6 through U11, count 16 mounting holes (3 x 6 - 2) starting from the bottom of the rack. The 16th hole is the first mounting hole of U6.

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