RAID (Redundant Array of Independent Disks) combines multiple physical drives into a single logical unit. Depending on the RAID level you choose, you gain redundancy, higher throughput, or both. RAID 1 mirrors data across two drives so that failure of one drive causes no data loss. RAID 5 distributes parity information across at least three drives, offering a good trade-off between capacity and fault tolerance. RAID does not replace backups because it protects neither against accidental deletion nor against ransomware. In an ISMS context, RAID configuration is part of availability assurance and should be documented in the asset register.