what is linux raid

In Linux, RAID refers to "disk array", which means "an array of independent disks with redundant capabilities". It mainly solves the storage speed problem of accessing data; it is composed of multiple independent disks. A technology that consists of a disk subsystem composed of high-performance disk drives, thereby providing higher storage performance and data redundancy than a single disk. The functions of RAID are: 1. Expand storage capacity; 2. Reduce the cost per unit capacity; 3. Increase storage speed; 4. Reliability; 5. Fault tolerance. If a single hard disk error occurs in a fault-tolerant array, it will not affect the entire system. of continued use.

#The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

What is RAID in a Linux system?

Disk array (Redundant Arrays of Independent Disks, RAID), which is composed of independent disks Array of redundant capabilities" means. Simply put, RAID is a technology that combines multiple independent hard drives in different ways to form a hard drive group, thereby providing higher storage performance and data backup than a single hard drive.

Redundant disk array technology was born in 1987 and was proposed by the University of California, Berkeley. To explain simply, N disks are combined into a virtual single large-capacity disk through the RAID Controller. The adoption of RAID brings huge benefits to storage systems, among which increasing the transmission rate and providing fault tolerance are the biggest advantages.

RAID disk array is characterized by accelerating the reading speed of N hard disks at the same time and providing fault tolerance Fault Tolerant, so RAID mainly solves the storage speed problem of accessing data, not the backup problem.

Based on the different combinations of disk arrays, RAID can be divided into different levels. Different technologies used in disk arrays for different applications are called RAID levels, and each level represents a different technology. The current industry-recognized standards are RAID 0~RAID 5.

What are the functions of RAID?

　①Expand storage capacity, which can be composed of multiple disks to form a huge storage space.

　② Reduce the cost per unit capacity. The price per megabyte of the largest capacity hard drive on the market is much higher than that of a popular hard drive. Therefore, the unit price of an array composed of multiple popular hard drives is much lower.

　③Improve storage speed. The improvement of the speed of a single hard disk is limited by the technical conditions of each period. It is often difficult to go further. Using RAID can allow multiple hard disks to share the reading or reading of data at the same time. write operations, so the overall speed is increased exponentially.

　④Reliability, the RAID system can use two sets of hard disks to synchronize mirror storage. This security measure is the most important for network servers.

　⑤Fault tolerance, a key function of the RAID controller is fault tolerance processing. If a single hard disk fails in a fault-tolerant array, it will not affect the overall continued use. The advanced RAID controller also has the function of rescuing data.

　⑥For IDE RAID, there is currently another function that supports ATA/66/100. RAID is also divided into two categories: SCSI RAID and IDE RAID. Of course, IDE RAID is much cheaper. If the host motherboard does not support ATA/66/100 hard drives, you can use the ATA/66/100 functions of the new hard drive through a RAID card.

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