You must allow 1 U (1.75 inches) of vertical space for each system you install in the rack.
NOTE: The vertical rails of the rack are marked by small indentations in
1 U (1.75 inches)
Figure 1-15. One Rack Unit
For more information about requirements for installing components in a rack, see the Dell Rack Advisor software available on the Dell World Wide Web site at
http://support.dell.com.
WARNING: If you are installing more than one system, install the slide assemblies so that the first system is installed in the lowest available posi- tion in the rack.