Direct answer
Retention can range from a few event clips to weeks or months, depending on camera count, resolution, frame rate, compression, bitrate, continuous versus event recording, recorder capacity, cloud plan, and overwrite policy. There is no responsible answer based only on the hard-drive label. Eight cameras recording continuously at high quality consume far more storage than two event-triggered cameras.
Define how far back the owner expects to investigate an event, then calculate storage with the exact camera settings and reserve operational headroom. Confirm what happens when storage fills, whether important clips can be locked, how exports are verified, and whether cloud retention differs from local. Longer retention also increases privacy and access-control responsibilities. Test that an ordinary user can find and export footage before the system is accepted.
How this answer was prepared
Camelback Smart Homes publishes this FAQ library for homeowners, design professionals, builders and property teams comparing integrated technology. Answers begin with the practical conclusion, then explain the factors that can change it.
Limitations: This is general educational information, not a site-specific design, quote, code determination or compatibility guarantee. Final requirements depend on the property, construction, infrastructure, equipment versions and project goals.