Start with measured bitrate and retention

The storage plan should begin with total average bitrate, recording hours and retention days. Resolution labels such as 4MP or 4K do not determine storage by themselves because codecs, frame rates, scene complexity and recorder settings can change bitrate significantly.

Use recorder statistics or camera configuration values when available. Add a reserve for formatting, metadata, exports, changing scenes and future camera additions.

Convert total bays into data-bearing bays

Mirrors, parity and hot spares reduce the number of bays that contribute usable capacity. A four-bay RAID 5 layout normally has three data-equivalent drives, while a four-bay RAID 6 layout has two. Recorder implementations vary, so confirm the actual storage mode.

Choose the smallest capacity with real headroom

The first capacity that barely fits today is often too small for a system that will add cameras, increase bitrate or extend retention. A practical plan leaves free space and at least one realistic growth step without requiring immediate replacement of every drive.

Do not ignore the exact model revision

The 12TB, 16TB and 20TB tiers contain multiple exact revisions with different cache and sustained-transfer figures. Cloudzat keeps those models separate, while many marketplace listings hide the revision behind a capacity selector.

Check the NVR maximum drive size

The chosen capacity must appear on the compatibility list for the exact recorder model and firmware. Older NVRs may support only smaller drives, may require a firmware update or may not address the entire capacity even when the drive powers on.

Use workload and AI streams as guardrails

SkyHawk AI supports up to 64 HD streams and 32 AI streams and is designed for a 550TB-per-year workload. If the plan exceeds those boundaries, redesign the system across more recorders or storage nodes rather than assuming a larger single disk solves the processing and workload problem.

Compare price per usable TB, not raw TB alone

Parity, spare drives and reserve change the effective cost. Compare the total drive purchase against usable retained footage, available bays, electricity and the cost of a future migration. A higher-capacity drive can be cheaper than adding another recorder chassis, but only when the recorder supports it.

Build a replacement and recovery plan

Surveillance arrays should have documented replacement models, tested footage exports, stable power and cooling, and a procedure for responding to SkyHawk Health Management or SMART warnings. Warranty replacement and Rescue services do not replace routine export of footage that cannot be recreated.