Understanding the RAID System
RAID stands for "Redundant Array of Independent Disks or Redundant Array of Inexpensive Disks" (redundant collection of inexpensive / independent disks). RAID is a method of combining several small, inexpensive hard drives into a disk pool that provides better performance and resiliency than a single larger, more expensive drive. However, from a computer perspective, the disk grouping appears as a single disk.
Redundant data storage, which is the duplication of all or part of the data stored on drives, helps protect the fault tolerance of the drive pool. This way, if one drive fails, data is preserved on the other operational drives.
There are several forms of RAID devices, all offering some level of fault tolerance, each with a specific tradeoff in functionality and performance.
The two most common forms of RAID are RAID 1 and RAID 5, described below: