Compare RAID 5, RAID 6, and RAID 10 for your NVR. Get usable capacity, drive count, and rebuild risk analysis — sized for your exact camera configuration.
RAID planning for surveillance is different from general storage. Cameras write continuously 24/7, which stresses RAID 5 rebuild operations differently than office file servers. This calculator computes the required raw storage from your camera specs, then determines how many drives you need under each RAID level to meet your retention target. It also evaluates rebuild risk: large RAID 5 arrays with drives over 8TB have a measurable probability of encountering an Unrecoverable Read Error (URE) during rebuild — and this calculator warns you when you're in that zone.
RAID 5 is the most common choice for small to medium deployments (4–12 cameras). It provides one drive fault tolerance and uses about 75–80% of raw capacity. RAID 6 is recommended for 16+ cameras or retention periods over 90 days — it survives two simultaneous drive failures, which matters during long rebuild windows. RAID 10 is best for high-performance NVRs with 50+ high-FPS cameras.
It depends on your cameras. As a rough guide: 8 cameras at 4MP H.265 (30-day retention) typically needs 2–4 drives of 4–6TB each in RAID 5. Use this calculator to get the exact drive count for your specific camera mix, resolution, and codec.
SATA hard drives have an Unrecoverable Read Error rate of 1 bit in 10^14 bits read. During a RAID 5 rebuild, the system reads every bit on every remaining drive. For arrays with large drives (8TB+), the probability of hitting a URE during rebuild becomes significant — potentially corrupting the rebuilt array. RAID 6 avoids this problem by tolerating two errors simultaneously.
RAID 5 with N drives wastes exactly 1 drive's worth of capacity for parity. RAID 6 wastes 2 drives. Example: 6 × 8TB drives in RAID 5 gives 40TB usable (83%). The same 6 drives in RAID 6 gives 32TB usable (67%). The extra protection of RAID 6 costs approximately 20% capacity compared to RAID 5.
RAID 0 (striping, no redundancy) is not recommended for surveillance. Any single drive failure causes complete data loss. CCTV storage is legally and operationally critical — the cost of re-recording is far higher than the cost of a few extra drives. Use RAID 5 at minimum.
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