Dell PowerEdge 2950 Installation Manual page 12

To mark the rack, perform the following steps:
1 Place a mark (or tape) on the rack's front vertical rails where you want to locate the bottom of the
system you are installing in the rack. The bottom of each 1-U space is at the middle of the narrowest
metal area between holes (marked with a horizontal line on some rack cabinets—see Figure 1-3).
2 Place a mark 88 mm (3.5 inches) above the original mark you made (or count up three holes in a rack
that meets EIA-310 standards) and mark the rack's front vertical rails with a felt-tipped pen or masking
tape (if you counted holes, place a mark just above the top hole). This mark or piece of tape indicates
where the system's upper edge will be located on the vertical rails (see Figure 1-3).
Figure 1-3. Marking the Vertical Rails
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Rack Installation Guide
1
1 marks on vertical rail (2)