Several terms related to servers

1. Server:

The English name of the server is "Server", which refers to a special dedicated computer system that provides various services to clients in a network environment. The "client" here refers to a PC installed with an operating system such as DOS, Windows 9x and other common user documentation. It can be seen from the concept of a server that a server is also a type of computer, except that it is a special computer that provides services for other computers and has unique characteristics that are different from ordinary computers.

2. The concept of U:
1U=1.75 inches=4.445cm. The computer room provides a U unit of space 4.5*58*62 cm (height*width*depth) to place a rack-mounted server and its ancillary equipment.

3.CPU (Central Processing Unit)

Central processing unit, CPU is the heart of the computer, including computing components and control components. It is the core for completing various operations and control, and is also the most important component that determines the performance of the computer. The main parameters are the main frequency of operation and the number of data bits transmitted or processed at one time.

4.Hard disk:
The hard drive is where the most important data is stored. Most of the data required for execution is read from the hard disk. Once the hard drive is damaged, no data can be used, so the hard drive is the most important device for storing data. The larger the capacity of the hard drive, the more data the server can store.


Hard drive capacity: It is often heard that hard drive space is 3.5GB or 4.5GB. GB is the unit of capacity. 1GB is approximately equal to one million bytes (Byte), which is also approximately equal to 1000MB. Of course, the larger the capacity of the hard drive, the better. The larger the capacity, the more data can be stored.


Hard drive speed: Hard drive speed refers to the speed of the hard drive motor. The faster the speed, the faster it can read and write data. Therefore, the faster the hard drive, the higher the price. The current hard drive speeds are commonly 5400 rpm and 7200 rpm.


5.Memory:
DDR: DDR (Double Data Rate) SDRAM provides dual memory bandwidth and is more efficient than SDR (Single Data Rate) SDRAM.
RAM: Random Access Memory RAM (Random Access Memory): RAM is memory that can be read and written. When we write data to RAM memory, we can also read data from RAM at the same time, which is different from ROM memory. However, RAM must maintain its own stability with stable and smooth power, so once the power is turned off, the data originally in the RAM will disappear.

ECC: Abbreviation for Error Checking and Correcting. It is widely used in computer instructions in various fields. Only after error correction in the memory can the computer operation instructions continue to be executed.

Most common errors in memory are: single-bit error, multiple-bit error, column error, and row error. They are all relatively similar. Single-bit errors mostly occur when one bit is wrong when reading a complete bit or word. When the same bit and word are always read with the same bit of data in error, it is called a multiple-bit error. Single-unit errors occur in many words, which are called column errors or row errors.

How these errors are corrected: ECC memory uses extra bits to store a code encrypted with data. When data is written to memory, the corresponding ECC code is also saved at the same time. When the data just stored is read back, the saved ECC code will be compared with the ECC code generated when the data was read. If the two codes are not identical, they are decoded to determine which bit of data is incorrect. The error bit is then discarded and the memory controller releases the correct data. Corrected data is rarely returned to memory. If the same erroneous data is read out again, the correction process is performed again. Rewriting data will increase the processing overhead, which will lead to a significant reduction in system performance. If the error is caused by a random event rather than a defect in the memory, the erroneous data at this memory address will be replaced by other data written again.

6.RAID:

RAID (Redundant Array of Independent Disks) storage technology improves the performance and reliability of data storage subsystems. The original purpose of developing RAID was to distribute large amounts of data into an array of small disks. To the server's operating system, these small disks acted like a "logical" hard drive.

Intel's integrated RAID controller and software help achieve the benefits of RAID for e-commerce applications in storage subsystems containing five, eight or more independent disks. Choosing RAID means that even if a hard drive fails, the server and network will remain fully operational with no data loss. In the early stages of RAID development, the "I" in RAID represented "price economy." As the cost of large-capacity hard drives dropped sharply, the industry gradually changed the meaning of the letter "I". It now means "independent ". This illustrates one of the main advantages of the RAID subsystem: independent disks, with the ability to protect data, improve network storage performance, and keep servers running.

A properly configured RAID array can help prevent server downtime, degraded network performance, and disruption to e-commerce applications when a hard drive fails.

Choosing RAID means that even if a hard drive fails, the server and network will remain fully operational with no data loss. In some cases, users on the network won't even notice that the hard drive has failed.

With the "hot-swap" feature supported by Intel's integrated RAID software, failed hard drives can be removed and replaced while the server is operating normally. The continued decline in the price of fast, large-capacity hard drives makes RAID an even more attractive storage technology for e-commerce businesses.

7. Traffic:

Network traffic reflects the number of packets passing through the network and how congested it is.
Byte: It is a unit of measurement of file size. It is also usually used to describe the size of a drive or disk. 8 bits = 1 byte.

8. Bandwidth:

It is used to measure the data transmission speed of a server connected to the INTERNET, in bps (bit per second).

Inbound bandwidth: From the server's perspective, we define input bandwidth (Inbound Bandwidth) as the speed at which data can be transmitted from the Internet to the server.

Outbound bandwidth: From the server's perspective, we define output bandwidth (Outbound Bandwidth) as the speed of data transmission from the server to the Internet.

The measurement unit of bandwidth is: Bit. Bit is called bit, which is the smallest unit of computer memory. 1 Bit has two variations: 0 and 1.