If you wish to buy a server rack you can use this buying guide.
Rack Units
U is the unit of measurement to describe the dimensions of the equipment. Each rack unit is 44.45 mm high.
Choosing the right height:
The height of the server rack is measured by U size.
Each rack unit is 44.45 mm high eg a 24 port patch panel = 1U
When you are buying equipment to put in the server rack, you need to pay attention to the U height.
If there is no U measurement, then you can use the shelves inside the cabinet racks (one shelf = 1U)
For example, a 42U server cabinet is 1867 mm high, but if you add a fan tray or castors then the height will be 2120 mm. So attention needs to be paid to the external measurements.
Choosing the right width:
Cabinet racks usually come in widths of 600mm and 800mm.
If you are including patching then the wider 800mm server is recommended.
Choosing the right depth:
It is important to ensure that cabinet racks provide sufficient depth, to provide sufficient working space.
RACK SUPPLIER LTD provide racks with 3 depths; 600mm, 800mm, 1000mm.