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When we talk about servers, we often talk about 2U servers or 42U servers, so what is U in the server?

Before you answer this question, you need to give a brief introduction to the server.

First, the server server, the English name Server, refers to the network equipment that can provide certain services. The main services provided include: data reception and transmission, data storage and data processing.

To be more popular, we can compare the server to a special computer without a monitor.

So my personal computer can also be used as a server?

In theory, a personal computer can be used as a server. However, the server is generally used in specific scenarios, such as financial enterprises, online shopping platforms and so on. In these scenarios, a data center composed of thousands of servers can store and process large amounts of data. Therefore, the personal computer can not meet the special needs in terms of performance, bandwidth, data processing ability and so on.

Servers are classified according to the shape of the product, which can be divided into:

Tower server: the most common type of server, a mainframe similar to a computer. This kind of server is large, independent and inconvenient for system management when working together, so it is mainly used for small enterprises to carry out business.

Rack server: a server that has a uniform appearance and is high in U units. This kind of server takes up small space and is easy to manage. It is mainly used in enterprises with large demand for servers, and it is also the most commonly used server.

Blade server: a rack chassis of standard height, a server in which multiple card server units can be inserted. It is mainly used in large data centers or areas that need large-scale computing, such as banking, financial industry and so on.

What is U? In the classification of servers, we learned that the height of rack servers is in U units. So, what on earth is U?

U (abbreviation for unit) is a unit that represents the height size of a rack server. The detailed dimensions of the U are determined by the American Electronic Industry Association (EIA), 1U=4.445 centimeters, 2U=4.445*2=8.89 centimeters, and so on.

U is not a patent for the server, it was originally a rack structure for communication switching, and then it was referenced to the rack of the server. At present, it is used as an informal standard for server rack structure, including specified screw size, hole distance, slide rail, and so on.

By specifying the size of the server by U, the server can be maintained in an appropriate size so that it can be easily installed on an iron or aluminum rack. There is a screw hole reserved in advance according to the server of different sizes on the rack, which is aligned with the screw hole of the server, and then fixed by screws.

The dimensions specified by U are the width (48.26cm = 19 inches) and height (multiples of 4.445 cm) of the server. The height of the server, that is, the thickness is based on U, 1U=4.445 centimeters. A rack that meets this requirement is sometimes called a "19-inch rack" because it is 19 inches wide.

Third, 1U servers, 2U servers, 4U servers in rack servers, the more common servers are:

1U server: server height is 4.445 cm

2U server: the height of the server is 4.445 "2cm" 8.89 cm

4U server: server height is 4.445cm "4cm" 17.78cm

The rack server looks not like a computer, but like a switch. Rack servers are installed in standard 19-inch cabinets. Most of this structure are functional servers.

In practical use, 1U or 2U servers are the most frequently used servers.

Because the service provider calculates the cost according to the space occupied by the server, using 1U server is the most space-saving and the lowest price. The scalability of 1U servers is not as good as that of 2U servers, with up to 4 hard disks and 2 slots for PCI. The scalability of 2U servers is better than that of 1U servers, with a maximum of 8 hard disks and 6 slots for PCI.

In the daily life of 4-or 19-inch cabinets, our mainframe is placed on the floor or on the table, but the server is placed in a special cabinet, that is, what we often call a "cabinet". Cabinets vary in size, but the most common is a standard cabinet with a width of 19 inches.

A 19-inch standard cabinet is a cabinet that can hold 19-inch rack servers. 19 inches = 48.26 centimeters, which refers to the width of the server, specifically the distance between the two lugs of a rack device. This is the structural standard of most rack equipment at present.

When equipment is installed in a 19-inch standard cabinet, the height of the equipment is expressed in units U, 1U=4.445 centimeters.

For devices that use 19-inch standard cabinets, the equipment panels are manufactured to the specification of nU (n represents an integer starting from 1). For some non-standard equipment, most of them can be fitted into a 19-inch chassis and fixed through an additional adaptation bezel.

Because many engineering equipment have a panel width of 19 inches, a 19-inch cabinet is the most common standard cabinet.

In addition to the 19-inch standard cabinet, the more common 42U cabinet is also a kind of standard cabinet.

The classification of 42U cabinets includes:

According to width and depth, 42U cabinet with width of 600mm and 800mm, depth of 600mm, 800mm, 900mm, 960mm, 1000 mm, 1100 mm, 1200 mm, etc.

According to the actual demand: in addition to the actual size of 42U, the width and depth can be customized according to the actual demand.

According to the above theory, we can infer that the 42U cabinet should be able to hold 42 1U servers. However, in fact, how many servers the 42U cabinet can hold needs to be calculated according to the specific equipment.

Because, 42U cabinets have to reserve space for heat dissipation and movement, space for wiring, and space for switches, firewalls, monitors and other devices after putting the server.

Finally, let's summarize the new knowledge we have learned from get today:

There are three kinds of servers: tower server, rack server and blade server.

The server is usually represented by U, 1U=4.445 centimeter

Common rack servers are: 1U, 2U, 4U

The common standard cabinets are: 19-inch cabinet, 42U cabinet

Servers are often placed in standard 19-inch cabinets

It should be noted that a 42U cabinet does not mean that 42 1U servers can be configured.

Guys, do you understand?

This article comes from the official account of Wechat: ZTE document (ID:ztedoc), author: ZTE document

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