RAIDnivåene

RAID, which stands for Redundant Array of Independent Disks, is a technology that combines multiple physical disk drives into one or more logical units to improve performance, storage capacity, fault tolerance, or a combination of these factors. Each RAID level defines a specific method for distributing data across the constituent drives. Because the levels differ in how they store parity information and balance data, they are chosen based on the required trade‑off between speed, reliability, and cost.

Level 0 (striping) splits data across two or more drives without parity or redundancy. It offers the highest throughput and effective storage capacity but cannot tolerate any single‑drive failure. Level 1 (mirroring) writes identical copies of data to two disks, providing robust data protection at the expense of doubling the disk cost and using only half the raw capacity for data.

Level 5 uses block‑level striping with distributed parity, which requires at least three disks. One disk’s capacity is used for parity data, allowing recovery from a single drive failure while preserving a large portion of capacity. Level 6 extends this with double parity and thus can survive two simultaneous failed drives, but needs at least four disks.

Levels 10, 50, and 60 combine striping and mirroring or striping with double parity, respectively. RAID 10 (mirrored striping) delivers high performance and strong fault tolerance, requiring an even number of disks. RAID 50 (striped 5s) and RAID 60 (striped 6s) blend the cumulative capacity and performance benefits of striping with the redundancy of levels 5 or 6, demanding large arrays for maximum effectiveness.

The choice of RAID level depends on the organization’s priorities. High‑performance, short‑term workloads may favor levels 0 or 10, whereas mission‑critical applications requiring data durability will typically use levels 5, 6, 50, or 60. Administrators must also consider backup strategies, as RAID does not replace proper data protection mechanisms.