RAID

Redundant Array of Independent Disks

Definition:

A data storage technology that combines multiple physical hard drives or solid-state drives into a single logical unit. Operating systems view a RAID setup as one drive, while the underlying controller distributes data across the array according to specific configurations (RAID levels).

Key Functions:

• Fault Tolerance (Redundancy): Protects against total data loss by writing parity data or duplicating files across multiple drives. If one drive physically fails, the system continues running, and the missing data can be rebuilt once the broken drive is replaced.
• Performance: Spreads read and write operations across multiple drives simultaneously (striping), increasing file transfer speeds compared to a single drive.

Common RAID Levels:

• RAID 0 (Striping): Splits data evenly across two or more drives for maximum speed. No redundancy—if one drive fails, all data is lost.
• RAID 1 (Mirroring): Duplicates exact copies of data across two drives. Provides strong data protection, but cuts usable storage capacity in half.
• RAID 5 (Striping with Parity): Requires at least three drives. Distributes data along with parity information across all disks, allowing the system to survive a single drive failure while balancing speed, protection, and storage capacity.
• RAID 6 / RAID 10: Advanced configurations providing protection against two simultaneous drive failures or combining mirroring with striping for maximum performance and security.

Important Note: RAID is designed for high availability and hardware reliability—it is not a backup. RAID protects against physical drive failure, but it does not guard against accidental file deletion, file corruption, ransomware, or disasters. A separate, offsite backup strategy (such as the 3-2-1 rule) remains essential.