在托管、購買服務器或者租用、使用機柜的時候，有時會聽到1U、2U、4U或者42U等類似這樣子的名詞。而這些名詞又代表什么意思呢?跟著快網小編一起來了解一下吧!

　　When hosting, purchasing servers, or renting or using server cabinets, sometimes we hear terms like 1U, 2U, 4U, or 42U. And what do these nouns represent? Follow the Quick Net editor to learn more!

　　關于“U”的單位U是一種表示服務器外部尺寸的單位，是unit的縮略語。規定了服務器的尺寸，可以使服務器以一定的尺寸放在機架上。機架上有固定服務器的螺孔，以便它能與服務器的螺孔對上號，再用螺絲加以固定好，這樣子可以方便安裝每一部服務器所需要的空間。

　　Regarding the unit of 'U', U is a unit that represents the external dimensions of a server and is an abbreviation for 'unit'. The size of the server is specified, which allows the server to be placed on the rack with a certain size. There are screw holes on the rack to fix the server, so that it can match the screw holes of the server, and then be fixed with screws to facilitate the installation of the required space for each server.

　　1U 2U 4U 服務器服務器規定的尺寸是服務器的寬(48.26cm=19英寸)與高(4.445cm的倍數)，厚度(高度))以4.445cm為基本單位。在機架式服務器尺寸當中，常見的就是1U服務器、2U服務器、4U服務器，這些服務器的尺寸是：1U=4.445厘米，2U=4.445*2=8.89厘米，4U=4.445*4=17.78厘米。在實際使用當中，1U或者2U服務器是非常經常使用的。因為服務商是根據服務器占用空間來計算費用的，所以采用1U服務器是非常節省空間的和價格非常低的，但是1U服務器的擴展性不如2U服務器的好。1U的硬盤數非常多可以插4個3.5寸，2U可以插8個3.5寸甚至更多，另外PCI的插槽數目也不同，1U非常多2個，2U的可以到6個。

　　The dimensions specified for a 1U 2U 4U server are the width (48.26cm=19 inches) and height (multiples of 4.445cm) of the server, with thickness (height) measured in units of 4.445cm. The common sizes of rack mounted servers are 1U servers, 2U servers, and 4U servers. The dimensions of these servers are: 1U=4.445 centimeters, 2U=4.445 * 2=8.89 centimeters, and 4U=4.445 * 4=17.78 centimeters. In practical use, 1U or 2U servers are the most commonly used. Because service providers calculate fees based on server space occupancy, using a 1U server is the most space saving and cost-effective option. However, the scalability of a 1U server is not as good as that of a 2U server. A 1U hard drive can accommodate up to 4 3.5-inch hard drives, while a 2U can accommodate 8 3.5-inch or even more. Additionally, the number of PCI slots varies, with a maximum of 2 for 1U and up to 6 for 2U.

　　42U機柜42U機柜一般的分類是：1)按寬度分：600mm和800mm寬的42U機柜，深度有：600mm,800mm,900mm,960mm,1000mm,1100mm,1200mm等;2)按實際需求分：除了實際使用尺寸是42U之外，寬度和深度可以按照實際需求定制。一個機柜所放的服務器是有限的，42U高度的機柜并不代表著實際能夠放42個1U服務器。放了服務器之后還要留散熱和挪動的空間，一些走線的空間，還有放交換機、防火墻、顯示器等其他設備的空間。所以一個42U機柜能放多少服務器，需要根據具體的設備來計算。那么問題來了，一個機柜一般部署多少臺服務器設備?一個機柜部署的服務器數量，要考慮很多參數，比如服務器的體積、功耗、發熱量等物理參數，還需要考慮機柜的供電、冷卻、承重等參數，如何確定能部署多少臺服務器，做決定時可以參考一下關鍵參數：1)預留：每個設備間預留1U以便散熱，預留交換機位置，考慮PDU位置;2)一般提供冗余10KW電源，靜態承載能力不小于1200kg(根據機房建設參數確定)3)不超電的前提下，一個機柜累計設備U數，一般不超過26U一個機柜，全1U設備部署數量一般不超過16臺，全2U設備一般不超過12臺，全4U設備一般4到7臺。

　　The general classification of 42U cabinets is: 1) Divided by width: 600mm and 800mm wide 42U cabinets, with depths of 600mm, 800mm, 900mm, 960mm, 1000mm, 1100mm, 1200mm, etc; 2) According to actual needs: In addition to the actual size of 42U, the width and depth can be customized according to actual needs. The number of servers that can be placed in one cabinet is limited, and a cabinet with a height of 42U does not necessarily mean that 42 1U servers can actually be placed. After installing the server, there should be space for heat dissipation and relocation, some wiring space, and space for other devices such as switches, firewalls, and displays. So how many servers can be placed in a 42U cabinet needs to be calculated based on the specific equipment. So the question is, how many server devices are usually deployed in one cabinet? The number of servers deployed in a cabinet needs to consider many parameters, such as physical parameters such as server volume, power consumption, heat generation, as well as parameters such as power supply, cooling, and load-bearing capacity of the cabinet. When deciding how many servers can be deployed, key parameters can be referred to: 1) Reservation: Reserve 1U between each device for heat dissipation, reserve switch positions, and consider PDU positions; 2) Generally, a redundant 10KW power supply is provided, with a static carrying capacity of not less than 1200kg (determined according to the construction parameters of the computer room). 3) Under the premise of not exceeding the power limit, the cumulative number of equipment U in a cabinet generally does not exceed 26U per cabinet. The deployment of all 1U equipment generally does not exceed 16 units, all 2U equipment generally does not exceed 12 units, and all 4U equipment generally ranges from 4 to 7 units.

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