RAID (Redundant Array of Independent Disks) combines multiple physical drives into one logical unit, trading off between speed, storage efficiency and fault tolerance depending on the level chosen. Here’s what matters when specifying it for a dedicated server.
RAID 0 — speed, no redundancy
Splits data across all drives with no duplication, giving the best possible read/write speed and full use of total capacity — but losing a single drive loses all data on the array. Suitable only for workloads where data is fully disposable or backed up elsewhere in real time, never for anything you can’t afford to lose.
RAID 1 — mirroring
Duplicates data identically across two drives. If one fails, the other keeps serving without interruption, and you simply replace the failed drive to restore redundancy. Usable capacity is half your total raw storage, but this is the simplest, most reliable option for a two-drive setup.
RAID 5 — balance of the two
Requires at least three drives; distributes data plus parity information across all of them, tolerating a single drive failure while losing only one drive’s worth of capacity to parity overhead. A good general-purpose choice, though rebuild time after a failure can be lengthy on very large drives.
RAID 10 — mirroring + striping
Combines mirrored pairs with striping across those pairs (minimum four drives). Offers both strong redundancy (can survive multiple drive failures, as long as not both drives in the same mirrored pair) and better performance than RAID 5, at the cost of also using half your total raw capacity. This is the common choice for database or high-write workloads that need both speed and fault tolerance.
Choosing for your workload
For anything running a production database or serving live customer traffic, RAID 1 or RAID 10 (never RAID 0) is the safe default — redundancy means a single drive failure is a routine, non-urgent replacement rather than a data-loss incident. RAID is not a substitute for backups: it protects against drive failure, not accidental deletion, ransomware, or a whole-server issue.