ERD Symbols and Meanings

The vector stencils library "Rack diagrams" contains 55 hardware symbols for creating the server rack layout diagrams using the ConceptDraw PRO diagramming and vector drawing software.
"A 19-inch rack is a standardized frame or enclosure for mounting multiple equipment modules. Each module has a front panel that is 19 inches wide, including edges or ears that protrude on each side which allow the module to be fastened to the rack frame with screws. Equipment designed to be placed in a rack is typically described as rack-mount, rack-mount instrument, a rack mounted system, a rack mount chassis, subrack, rack mountable, or occasionally simply shelf. The industry standard rack cabinet is 42U tall." [19-inch rack. Wikipedia]
"A rack unit, U or RU is a unit of measure that describes the height of equipment designed to mount in a 19-inch rack or a 23-inch rack. The size of a piece of rack-mounted equipment is frequently described as a number in "U". For example, one rack unit is often referred to as "1U", 2 rack units as "2U" and so on.
A typical full size rack is 42U, which means it holds just over 6 feet of equipment, and a typical "half-height" rack would be 18-22U, or around 3 feet high." [Rack unit. Wikipedia]
The example "Design elements - Rack diagram" is included in the Rack Diagrams solution from the Computer and Networks area of ConceptDraw Solution Park.