What is a unit, the size of the unit.

Unit – what is it?

Unit (Unity) – an informal unit of measurement used in the IT industry to standardize the size of equipment. It is denoted by the Latin letter U and is calculated in relation to the height of the instrument unit. Be sure to be indicated in the technical passport of the equipment. For example: uninterruptible power supply, height 5U.


Why did you need to invent a unit?

The invention of a special unit of measure “unit” is the second wave of global (literally worldwide) standardization. The first was associated with the widespread introduction of a metric thread, which made it possible to put on the conveyor an assembly of machines and the manufacture of interchangeable parts for them.

Now nobody is surprised that a nut from a mining truck can be used on a passenger car, although at the beginning of the last century every detail could be unique ..

The same thing happened at the end of the twentieth century, when IT-technologies ceased to be a lot of a narrow circle of professionals and became the property of millions. It turned out that the only possible way to locate the largest possible number of hardware units on a unit of area is to place them in a pile and form hardware racks .

From this emerged a reasonable requirement that the height of the cubes (hardware units) in the rack should be either the same size or multiple to an integer number.

Who invented the unit of measure of the height of the hardware block, and why he chose just such a size is not known for certain. But thanks to this person, a computer unit made in Taiwan easily gets into a hardware rack in Moscow, New York or at a research station in Antarctica.

Unit is how much? What is the height of a single unit in centimeters.

Unit – conditional unit of measurement. Like the archaic “elbow”, which our ancestors used without thinking. Just because it was convenient for them. If the unit is correlated with the usual units of measurement, then it turns out that it is 1.75 inches, or 4.45 centimeters.True, life has slightly corrected this parameter. After all, the block can not be put on each other, like a box. Any gap between them should remain. Therefore, the real unit is less than that invented by 0.7 mm (one thirty-second inch) and is equal to 43.7 mm.Our services: 
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A unit is a convenient way to calculate the cost of rack space.

Using a standard unit of measurement has 2 main advantages. Firstly (and above all), having this unit of measurement, it is very convenient to install equipment in data centers. Floor to ceiling racks are placed with holes. Every three holes in the rack – this is one unit. Installation of the server rack is similar to the assembly of the children’s designer.Secondly, and this is commerce, with the help of a unit it is convenient for the owner of the data center to indicate the price for the provision of equipment placement services (how much the cost of placing 1 server will cost). He announces the price of the unit, and the owner of the equipment knows exactly what his placement at the provider site will cost him.