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Friday, May 10, 2019

Linux SysAdmin] 2. What is a server?

People who are interested in server hardware maybe have thought about it once. 'What is a server?' A server is a device or software that provides a service. 

For example, you might be using a Wi-Fi router at home. When you get home, your smartphone will automatically get an IP address from it and you will use the Internet through it. So what service does the Wi-Fi router provide for your smartphone? 

It is a DHCP service. The Wi-Fi Router acts as a DHCP server and your smartphone as a DHCP client. In other words, the DHCP server software is installed on your Wi-Fi router and the DHCP client software is installed on your smartphone. A client is a device or software that accesses a service provided by a server. 

In general, when people hear the server, they will think of the following hardware:


But a device that provides a service can be called a server.

What is different between a server and a desktop?

Anyway, let's take a look at the server. How is it different from the desktop you use at home?

The first is a price difference. The server is more expensive than the desktop. In general, servers use larger and more expensive components than desktop. For Example, the following kinds of CPU are installed within the x86 desktop and the x86 server.

Desktop
x86 Server
 - Intel Core X Processor
 - AMD Ryzen Processor
 - Intel Xeon E Processor
 - AMD EPYC Processors


What companies are the x86 server manufacturer? HP, Dell, Fujitsu, Lenovo, Gigabyte, ASUS, Tyan, Supermicro and so on. Examples of Unix server CPUs are IBM Power CPU and Oracle SPARC CPU. Have you ever thought about how expensive a server CPU would be?



The second is performance. The desktop usually uses a single CPU. But the server can use multiple CPUs. The Intel Xeon E5 product support two and four-socket systems. And The Intel Xeon E7 product support from two to eight sockets. Unix processor product support up to dozens of sockets systems.

How much memory supported per CPU?

Intel Core i9
Intel Xeon Platinum 9282
AMD EPYC 7601
 128GB
 2TB
 2TB

How many cores supported per CPU?

Intel Core i9
Intel Xeon Platinum 9282
AMD EPYC 7601
 16
 56
 32

How peaceful will be the programs running on a system with 4TB memory? I would like to use such a system. :D

The third is the availability. You will turn off your desktop when work is finish, but the server should be stable 24/7. Servers are designed to provide reliable services in a mission-critical enterprise environment and are typically installed and operating in a data center. Stable power supply, optimum temperature, and humidity maintenance, the dust-free environment is very important.


Certain parts of the server are modular and are designed to be easily replaceable if they fail. Also, it has a fault-tolerant structure. For example, the power supply has an N + 1 structure. So even if one power supply fails, the server service goes back to normal.

The fourth is scalability. After the server is installed, it is likely that the service will gradually increase over time. Depending on the service load, CPU power may be needed more and there may be insufficient memory size for applications or storage capacity for data. At the point, the server should be able to be scalable enough for the resources you need.


For example, suppose you installed an FC HBA card on a server and then connected it to a SAN network and allocated a certain amount of external storage space for storing data. When storage space runs out at some point over time, it must be able to increase external storage capacity and allocate additional space to servers without rebooting.

So far, you've looked at the features of the server.

I am not familiar with English yet and I don't know if it was explained well. It will improve gradually. So see you next post. Thank you.



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