RAID stands for Redundant Array of Inexpensive Disks or Redundant Array of Independent Disks. It is a technology for saving or storing data in multiple places like hard disks to protect data from drive failure, and it also increases the reliability of data storage.
RAID works by querying data into multiple disks. It allows input/output operations to overlap in a balanced way. The software that performs RAID functionality and controls to drive can either be located on a separate hardware RAID controller or simply be a drive. You can save data in case of a crash by using the RAID controller.
RAID system can be used with a number of interfaces like SATA, SCSI, or FC (Fiber Channel). The RAID system is consist of two or more drives working in parallel. It may be a hard disk but there is also a trend of using technology for SSD (Solid States Drive).
There are different RAID levels, however, many variations have developed. These RAID levels are optimized for specific situations.
In the system of RAID 0, the data can be split into blocks and spread the split data into multiple disks like a hard disk. It only strips the data, with no mirroring or parity. It offers the best performance without fault tolerance.
The data will be lost in case of any drive failure because stripping divides or spreads the data among all drives in the set.
RAID 1: Mirroring
RAID 1 is known as Mirroring, as the name declares that it mirrors the same data into two disks. This array basically needs 2 disks. It increases the read performance over 1 disk up to 2x. In case of 1 drive failure, the data can be restored by using disk 2. It is a good choice for high availability and high-performance application.
RAID 5: Striping with parity
RAID 5 consists of block-level striping distributed parity. It is the most common and secure level. It requires at least 3 disks and can work up to 16 disks. The data parity is written on one drive. It distributes parity information on all disks among drives, requiring all drives but at least one drive to be present to operate. The striping in the system allows users to reconstruct data in case of 1 drive failure.
RAID 6: Striping with double parity
RAID 6 is like RAID 5, but it writes parity information on 2 drives. It is a scheme that works by placing data on multiple disks. It also allows input/output I/O operations to overlap in a balanced way and improve performance. It requires 4 disks minimum. It minimizes the problems mostly associated with RAID 5.
RAID 10:Combining striping and parity
RAID 10 is also known as RAID 1+0, it combines disk mirrors and disk striping to protect and save data. At this RAID level, it is possible to combine the advantages of RAID 1 and 0. It offers high performance at a much higher cost. It requires a minimum of 4 disks. As long as one disk in each mirrored pair is functional, the data can be retrieved or recovered.