GLOSSARY
What is RAID?
RAID stands for Redundant Array of Independent (or Inexpensive) Disks. It’s a storage technology that combines two or more physical drives into a single logical unit to enhance performance, reliability, or sometimes both.
Developed in the late 1980s by Patterson, Gibson, and Katz at UC Berkeley, RAID emerged as a way to outperform costly mainframe drives using an array of cheaper disks with added redundancy for reliability
Why RAID matters
RAID can:
- Boost performance by spreading (“striping”) data across multiple disks for faster reads/writes.
- Enhance redundancy, protecting your data if a disk fails.
- Expand usable capacity by aggregating several drives into one large pool.
The choice of RAID level depends on balancing speed, fault tolerance, and storage efficiency
Common RAID Levels
| RAID Level | Key Features | Pros | Cons |
|---|---|---|---|
| RAID 0 (Striping) | Splits data evenly across ≥2 drives | Maximum speed, full capacity | No redundancy – failure = total data loss |
| RAID 1 (Mirroring) | Duplicates data across ≥2 drives | Excellent redundancy, simple recovery | Only uses half the total capacity |
| RAID 5 (Striping + Single Parity) | Needs ≥3 drives, includes parity for recovery | Good balance: performance, protection, capacity | Can handle one drive failure |
| RAID 6 (Striping + Dual Parity) | Needs ≥4 drives, supports two failures | Stronger fault tolerance | Higher overhead, slightly slower writes |
| RAID 10 (RAID 1+0) | Mirrors stripes (min 4 drives) | Best mix: speed + redundancy | Uses 50% of total capacity |
Beyond these, there are hybrid or nested RAID levels (e.g., RAID 50, RAID 60), but the table above covers the most commonly used ones
How RAID Works
- Striping: Data gets split into chunks and written across multiple disks simultaneously to boost speed
- Mirroring: Every piece of data is duplicated on another disk — giving you a real-time backup
- Parity: Error-correction data is calculated and stored (separately or distributed) to rebuild lost data when a drive fails
When to Use RAID
- RAID 0: Ideal for temporary scratch disks or gaming but risky for valuable data.
- RAID 1: Excellent for OS drives or personal files simple and reliable.
- RAID 5: Great for general NAS and home servers balanced protection and capacity.
- RAID 6: Recommended for larger arrays where extra safety matters.
- RAID 10: Optimal for performance-critical tasks like databases or virtualization.
Remember: RAID helps protect against drive failure, not against other issues like accidental deletion, malware, or disasters. It’s a piece of a broader backup strategy