RAID is an abbreviation of Redundant Array of Independent Disks in English. Translating it into Chinese means "redundant array of independent disks", sometimes referred to as "Disk Array" for short.

Simply put, RAID is a method of combining multiple independent hard disks (physical hard disks) in different ways to form a hard disk group (logical hard disk), thereby providing higher storage performance and providing data backup technology than a single hard disk. The different ways of making up a disk array become RAID levels. The function of data backup is to use the backup information to restore the damaged data once the user data is damaged, thus ensuring the security of the user data. At the user's point of view, the composed disk group is like a hard disk, and the user can partition it, format it, and so on. In short, the operation of the disk array is exactly the same as a single hard disk. The difference is that disk array storage speed is much higher than a single hard disk, and can provide automatic data backup.

Two major characteristics of RAID technology: First, speed, and second, security, due to these two advantages, RAID technology was applied to the SCSI interface in the advanced server hard disk system, with the development of computer technology in recent years, the PC's CPU The speed has entered the GHz era. IDE interface hard disk is not far behind, has introduced ATA66 and ATA100 hard drives. This makes it possible for RAID technology to be applied to medium-to-low-end or even personal PCs. RAID is usually implemented by a RAID controller in a hard disk array tower or a RAID card in a computer.

RAID technology has evolved and now has from RAID 0 to 6 of the seven basic RAID levels. In addition, there are some basic RAID level combinations, such as RAID 10 (combination of RAID 0 and RAID 1), RAID 50 (combination of RAID 0 and RAID 5), and so on. Different RAID levels represent different storage performance, data security, and storage costs. However, the most commonly used are the following RAID types.