A server rack is a standard frame used for mounting server rack modules inside a data center server rack frame infrastructure. On a 19-inch rack, multiple equipment modules can be easily mounted, wherein each module has 19 inches wide front panel. Rack servers are available in different sizes, such as IU, 2U, and 4U. 42U tall rack is an industry standard rack cabinet. Generally, equipment designed to be mounted in a rack cabinet are also referred as rack-mounted system, rack-mount, rack-mount instrument, subtrack, shelf, or rack mountable.
Typically, racks are available in two or four vertical posts, wherein the four post racks provide support to the equipment from the front and rear. On the other hand, two post racks are commonly used in telecommunication installations, and allows equipment to be mounted through its front panel holes, or near to its center of gravity. The mounting of piece of equipment completely depends on the design of the rack.