RAID combines several disks so recorded video survives a drive failure. Mirroring keeps two identical copies; parity spreads redundancy across disks; striping with parity adds capacity and speed. RAID protects availability, not the data against deletion, corruption, theft or fire.
A recorder writes continuously for years, so disks fail eventually. RAID decides whether that failure is an outage or a notification.
Choosing a RAID level
Mirroring is simple and rebuilds quickly but halves usable capacity. Parity layouts use space efficiently yet rebuild slowly and stress the remaining disks. A second recorder covers what no single chassis can.
Maintenance and limits
Monitor disk health, replace failed drives promptly and make sure alerts reach someone. Keep a separate copy of footage that matters, because RAID mirrors a deletion as faithfully as it mirrors a recording.