Master RAID in One Minute: Quick Guide to Disk Array Types & Benefits

One Powerful Diagram to Understand RAID Disk Arrays in One Minute

Overview: This article consolidates all RAID technologies and principles with accompanying diagrams, explaining what RAID is, its classifications, underlying principles, level-specific diagrams, and methods for implementing both software and hardware RAID.

RAID ( R edundant A rrays of I ndependent D isks)

RAID technology is broadly divided into two types: hardware‑based RAID (

硬RAID

) and software‑based RAID (

软RAID

).

RAID levels include RAID 0, RAID 1, RAID 2, RAID 3, RAID 4, RAID 5, and the combined RAID 0+1 (also known as RAID 10).

Deployment Methods

Stand‑alone (single‑node) : A single server provides the service, with only one instance deployed.

Cluster : Multiple servers provide the service simultaneously, offering redundancy so that if one node fails, the service remains available.

Hot‑swap (hot‑standby) : One primary server serves while a standby server automatically takes over if the primary fails.

Advantages and Disadvantages of Each RAID Level

RAID 0 : Highest access speed, no fault tolerance.

RAID 1 : Full fault tolerance, but high cost.

RAID 2 : Uses Hamming code for error correction, high redundancy, slower performance.

RAID 3 : Best write performance, lacks multitasking capability.

RAID 4 : Supports multitasking and fault tolerance, but the dedicated parity disk becomes a performance bottleneck.

RAID 5 : Supports multitasking and fault tolerance; write operations incur overhead.

RAID 0+1 / RAID 10 : Combines speed and full fault tolerance, but at higher cost.

RAID 0 (striping): Distributes consecutive data across multiple disks, allowing parallel access and delivering high storage performance.

RAID 1 (mirroring): Replicates data completely onto another disk, providing high safety but only 50% space utilization.

RAID 0+1 : A hybrid of RAID 0 and RAID 1, offering both speed and safety, commonly used by enterprises with ample budgets.

RAID 5 : A compromise between RAID 0 and RAID 1; reads are relatively fast, safety is high thanks to parity for data recovery, and space utilization is efficient. It is widely adopted by internet companies.

RAID 1+0 : Combines RAID 0 and RAID 1, delivering both high speed and high safety, suitable for well‑funded enterprises and cloud providers, often implemented with SSDs for optimal performance.

Source: Adapted from the “Operations Tribe” public account.