AI video surveillance server: how to size cameras, disks and GPU

Recorder (NVR) or server?

An NVR is a closed appliance: it records a fixed number of cameras and little else. For a shop with a few cameras it may be enough. A server running video management software (VMS) takes far more cameras, AI analytics, several control stations, integration with alarms or access control, and grows with disks and GPUs.

How much each camera takes up: the calculation

The key figure is each camera’s bitrate (Mbps), which depends on resolution, frames per second, codec and scene. The calculation is simple: Mbps × 86,400 seconds ÷ 8 = MB per day.

A 4-megapixel camera in H.265 at about 4 Mbps takes up about 43 GB a day. Sixteen cameras for 30 days come to about 21 TB of usable space, plus the space RAID takes and a 20% margin. Recording on motion only reduces it a lot, but size for the worst case: a rainy night or a moving tree means almost everything gets recorded.

Disks and RAID for non-stop recording

Recording writes around the clock: use surveillance or enterprise-class disks, designed for continuous writing. With many disks, RAID 6 survives two failing at once; a hot spare shortens rebuild time. The system and the VMS database are best on a separate SSD.

AI analytics: when you need a GPU

Detecting people or vehicles, line crossing or loitering means decoding every video stream and running the images through a model. The GPU does both: hardware video decoding and inference. How many cameras it analyses at once depends on resolution, the frames per second analysed and the model, which is why it should be sized with the software you will use.

Network: cameras apart and secure access

Cameras should sit on their own network (a VLAN or a dedicated switch), separate from the office computers: a camera is one more connected device, and it should not be a way into everything else. Also check the switch’s PoE budget: the total the cameras draw, with headroom for night-time infrared.

To view cameras remotely, a VPN is better than opening the recorder’s ports to the internet.

Retention and data protection

Video of people is personal data under the GDPR. In Spain, for example, the law requires recordings to be deleted within one month at most, unless they must be kept to evidence an incident; check the rule in your country. Signpost the area, limit who can access the footage and avoid recording public space beyond what is strictly necessary. Keeping recordings on your own server, inside your network, makes it easier to control who sees them.

Indicative starting points