Here are some tips about buying the right-sized server rack for your environment:
(1) Select a server rack with sufficient internal space to house your current equipmentand ensure that you have ample space to accommodate planned future expansion as well as any unplanned equipment purchases. Rackmount equipment is measured in the Electronic Industries Alliance (EIA) standard "Rack Units" or Rack "U". One "Rack Unit" is equal to 1.75" in height. Keep in mind that space for accessories, such as environmental monitoring devices, remote power management devices, rack mount LCD monitors, and battery back-up, may be necessary. For example, if you need to accommodate 20 2U servers, you would likely want to choose a rack with a height of 44U to accommodate accessories such as a 1U patch panel, as well as a 2U UPS back-up battery.
(2) A rack’s internal height is measured from the tallest point of any side rail to the bottom chassis; internal depth is measured from the insides of both front and rear doors; and internal width is measured from one side panel to the other.
(3) Be sure that the rack’s external dimensions can be accommodated in the floor space allotted for it, check that it can be safely moved through all doorways, and ensure that its placement meets any relevant clearance or safety regulations.
To read more tips about buying server racks, visit: http://www.42u.com/server-rack-article.htm or http://www.server-rack-online.com/server-rack-information.html.