What is the main purpose of a RAID disk array?

This article introduces you to the main purpose of RAID disk array. First, RAID is the abbreviation of English Redundant Array of Independent Disks. Chinese is referred to as independent redundant disk array. Simply put, RAID is a combination of multiple independent hard disks (physical hard disks) in different ways to form a disk group (logical hard disk), which provides higher storage performance and data backup technology than a single hard disk. The different ways of composing a disk array become RAID Levels. The function of data backup is to use the backup information to recover the damaged data after the user data is damaged, thus ensuring the security of the user data. In the user's view, the composed disk group is like a hard disk, the user can partition it, format it and so on. In summary, the operation of the disk array is exactly the same as a single hard disk. The difference is that disk arrays are much faster than a single hard disk and can provide automatic data backup.

What is the main purpose of a RAID disk array?

Although RAID contains multiple hard drives, it appears as a standalone large storage device under the operating system. There are three main benefits to using RAID technology in storage systems:

Provide disk spanning by grouping multiple disks together as one logical volume;

Increase the speed of accessing the disk by dividing the data into multiple blocks (blocks) to write/read multiple disks in parallel;

Provide fault tolerance through mirroring or verification operations;

The main purpose of the initial development of RAID was to save costs. At that time, the price of several small-capacity hard disks was lower than that of large-capacity hard disks. At present, the role of RAID in terms of cost savings is not obvious, but RAID can take full advantage of multiple hard disks, achieving speed and throughput far beyond any single hard disk. In addition to performance improvements, RAID also provides good fault tolerance, and can continue to work in the event of a problem with any hard drive, without being affected by the damaged hard drive.

RAID technology is divided into several different levels that provide different speeds, security, and price/performance. Choosing the appropriate RAID level based on the actual situation can meet the user's requirements for storage system availability, performance, and capacity. Commonly used RAID levels are as follows: NRAID, JBOD, RAID0, RAID1, RAID1+0, RAID3, RAID5, etc. RAID5 and RAID (1+0) are often used today.

Disk Array is a technology that uses a hard disk controller to control the interconnection of multiple hard disks, synchronize the read and write of multiple hard disks, reduce errors, and increase efficiency and reliability. Disk array cards are hardware products that implement this technology. Disk array cards have a dedicated processor and special storage for caching data. The operation of the disk using the disk array card server is directly processed by the array card, so a large amount of CPU and system memory resources are not required, and the performance of the disk subsystem is not degraded. The processing unit dedicated to the array card operates, and its performance is much higher than that of a conventional non-array hard disk, and it is safer and more stable.

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