Dell PowerEdge R905 - Manual (Page 13)

Dell™ Rack Installation Guide
11
Marking the Rack
You must allow 4 U (7 inches) of vertical space for each system you install
in the rack (see Figure 1-3).
NOTE:
Your rack may already be marked and not require this procedure.
Figure 1-3. One Rack Unit
CAUTION:
If you are installing more than one system, install the slide assemblies
so that the first system is installed in the lowest available position in the rack.
To mark the rack, perform the following steps:
1 Place a mark on the rack’s front vertical rails where you want to locate
the bottom of the system you are installing in the rack cabinet.
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 1-4).
1 U (44 mm or 1.75 inches)
12.7 mm (0.5 inch)
15.9 mm (0.625 inch)
15.9 mm (0.625 inch)
12.7 mm (0.5 inch)