RAID
RAID
RAID (Redundant Array of Independent Disks) is a data storage virtualization technology that combines multiple physical disk drives into one or more logical units for the purposes of data redundancy, performance improvement, or both. Originally known as "Redundant Array of Inexpensive Disks," the term was later redefined to emphasize independence rather than cost.
RAID uses techniques such as mirroring, striping, and parity to distribute data across the array. Different RAID levels provide different balances of performance, fault tolerance, and storage capacity.
Common RAID Levels
| RAID Level | Description | Minimum Disks | Fault Tolerance | Use Case |
|---|---|---|---|---|
| RAID 0 | Striping (no redundancy) | 2 | None | High-speed temporary storage |
| RAID 1 | Mirroring | 2 | 1 disk | Critical data redundancy |
| RAID 5 | Striping with distributed parity | 3 | 1 disk | Balance of speed and fault tolerance |
| RAID 6 | Striping with double parity | 4 | 2 disks | High-redundancy for larger arrays |
| RAID 10 | Nested RAID 1+0 | 4 | Up to 2 disks (depends on failure pattern) | High performance and redundancy |
Types of RAID
- Software RAID – Managed by the operating system using tools such as
mdadmon Linux. - Hardware RAID – Managed by a dedicated RAID controller with its own firmware and CPU.
- Fake RAID – BIOS-based RAID with some reliance on operating system drivers.
Usage
RAID is commonly used in:
- Servers and data centers to ensure high availability and fault tolerance
- Workstations requiring high disk performance (e.g., video editing)
- Network-attached storage (NAS) systems
- Backup systems
While RAID provides redundancy, it is not a replacement for backups. It protects against hardware failure but not against data corruption, accidental deletion, or malware.
