RAID stands for "Redundant Array of Independent Disks". It is a way of storing the same data in different places on multiple hard disks or solid-state drives (SSDs) to protect data in the case of a drive failure. RAID combines multiple physical disk drive components into one or more logical units for the purposes of data redundancy, performance improvement, or both. RAID levels refer to the different schemes or data distribution layouts used to distribute data across the drives, depending on the required level of redundancy and performance. The different RAID levels provide a different balance among the key goals: reliability, availability, performance, and capacity.

Here are some of the most common RAID levels:

• RAID 0: Striping for Performance. Data is split evenly across two or more disks, which can improve performance but provides no data redundancy.

• RAID 1: Mirroring for Fault Tolerance. Data is duplicated on two or more disks, providing 100% data redundancy.

• RAID 5: Speed and Fault Tolerance. Data is striped across three or more disks for performance, and parity is computed for fault tolerance.

• RAID 10: Combines RAID 1 mirroring with RAID 0 striping for both safety and performance.

RAID can be implemented through software or hardware. Software RAID can be implemented through features that combine multiple disk devices connected directly to a host computer, while hardware RAID uses a control component independent of the host CPU to implement RAID.

RAID can provide data security with solid-state drives (SSDs) without the expense of an all-SSD system. For example, a fast SSD can be mirrored with a mechanical drive. RAID is used in desktop computers by gamers for speed and by business users for reliability.