What is RAID?

What is RAID?

RAID stands for Redundant Array of Independent Disks, and it is a way of combining multiple physical drives into a single logical unit. Depending on the RAID level, you can get better performance, data redundancy, or both. RAID is commonly used in servers and workstations where data availability and speed are critical.

RAID 0 is all about speed. It splits data across two or more drives in a process called striping. If you have two drives in RAID 0, you can read and write data twice as fast because each drive handles half of the data. The downside is that if either drive fails, you lose all your data. There is no redundancy. RAID 0 is great for scratch disks and temporary files, but never for important data.

RAID 1 is all about safety. It mirrors data across two drives. Everything written to one drive is also written to the other. If one drive fails, the other has a complete copy of all data. Read performance is improved because the controller can read from both drives simultaneously, but write performance is the same as a single drive. RAID 1 is simple and effective, but you lose half your total capacity to redundancy.

RAID 5 and RAID 6 offer a balance of performance and redundancy. RAID 5 uses three or more drives and stripes data with parity information. If one drive fails, the parity data can be used to reconstruct the missing data. RAID 6 is similar but uses two parity blocks, allowing for two drive failures. Both offer good read performance and efficient use of capacity, but write performance is slower because of the parity calculations.

RAID 10 combines mirroring and striping. It requires four drives and creates a striped set of mirrored pairs. This gives you both the speed of RAID 0 and the redundancy of RAID 1. RAID 10 is often the best choice for performance-critical applications that also need data protection, like database servers. The downside is that you only get half of your total capacity for actual data storage.