CCTV Storage — Drives, RAID and Retention Planning

Storage is where CCTV projects most often fail at handover — either the recorder runs out of space sooner than the customer expected, or a drive fails mid-incident and footage is lost. This section walks through how to size, specify, and protect storage so neither happens.

Topics covered in this section

The lessons explain why surveillance-rated drives (Purple, Skyhawk, IronWolf and equivalents) behave differently from desktop drives under continuous write load, when RAID 1, RAID 5 or RAID 6 is justified on small and medium sites, and how to calculate retention in practice from camera count, resolution, frame rate, codec, motion-detection ratio and required days of footage. There is also a section on offsite redundancy — cloud secondaries and on-prem hot spares — for sites that cannot afford an evidence gap.

Storage sizing in real-world numbers

By the end you should be able to look at a sixteen-camera, 4 MP, H.265, 30 day specification and quote a credible drive count and RAID configuration without reaching for a vendor calculator. This module is one of several in the wider CCTV Course on bhcourses.ie, alongside basics, IP cameras, NVRs and troubleshooting. The same retention exercises and worked examples appear in the more detailed CCTV Storage module on the bhcourses.com training catalogue.

Common mistakes addressed

Underspecifying capacity for H.265 sites that get reconfigured to H.264 mid-project, mixing drive models inside a single RAID, leaving SMART monitoring disabled, and ignoring rebuild times on large-volume RAID 5 are all covered with the warning signs and the fix.