Choosing an NVR for a UAE Business: Channels, Storage and Retention

Three numbers decide the recorder: how many cameras it must take today, how many days of footage you must keep, and the total bitrate those cameras produce. Get the third one wrong and the recorder either overwrites your evidence early or costs far more than it needed to.

Channels: buy the next size up, once

Recorders come in 4, 8, 16, 32 and 64 channel bodies. Camera counts almost never go down, and a site that installs eight cameras adds two more within a year, usually at the loading bay or the back corridor nobody thought about.

Buy one size above today's count. Going from eight cameras to nine on an eight channel recorder means buying a second recorder and running two systems, which is worse than paying a little more once.

Check the recorder's total incoming bandwidth as well as its channel count. A 16 channel unit with a modest input ceiling cannot take 16 high resolution cameras at full frame rate, and the datasheet states both numbers.

The storage calculation, done properly

Storage is arithmetic, not guesswork. The formula is bitrate multiplied by time.

One camera at 4 megabits per second produces 4 megabits every second, which is 0.5 megabytes per second, about 1.8 gigabytes per hour, and roughly 43 gigabytes per day of continuous recording. Sixteen of those cameras produce about 691 gigabytes a day. Hold that for 30 days and you need roughly 20 terabytes before any overhead or redundancy.

Work your own numbers the same way. Ask the installer for the configured bitrate per camera rather than the resolution, because resolution alone does not determine file size. A 4 megapixel camera with heavy compression and a 4 megapixel camera at high quality can differ by a factor of three.

Two things reduce the total honestly. Motion or event based recording cuts storage substantially on sites that are quiet at night, provided detection is tuned so it does not miss the event you care about. Modern compression, which vendors market under various names, reduces bitrate on static scenes and is worth enabling where the cameras support it.

How long to keep footage

Retention is a business and compliance decision before it is a technical one. Incidents are frequently reported days after they happen, and a system holding seven days has often already overwritten the footage by the time anyone asks.

Thirty days is the common baseline for a UAE commercial site. Some sectors and some landlords require longer, and premises with specific licensing requirements can be subject to their own rules. Check the requirement that applies to your activity and your building with the relevant authority before you size the disks, because retention is the input that drives the cost, and doubling it doubles the storage.

Disks: use surveillance rated drives

Surveillance drives are specified for continuous sequential writing from many streams at once, which is a different duty cycle from a desktop drive. Using desktop drives in a recorder is the most common reason a system fails silently in its second year.

Plan for redundancy on anything that matters. A single drive failure in a system with no redundancy loses the recordings, and drives fail. Larger systems should use a redundant array; small ones should at least be monitored so somebody learns about a failed disk before an incident does.

Also plan for heat. Recorders are often installed in unventilated cupboards, and disk life falls as temperature rises. In a UAE building where cooling is reduced at weekends, that cupboard gets hot. Ventilate it and alert on temperature.

The features that earn their place

• PoE ports built in. A recorder with integrated PoE simplifies small installations considerably. For larger sites, use proper switches instead, and size the power budget as described in our guide to choosing a network switch.
• Camera compatibility. Mixed vendor systems work, but feature support varies. If you want analytics, two way audio or specific camera controls, confirm support against the exact camera models.
• Analytics that reduce noise. Line crossing and intrusion detection with person and vehicle classification cut false alarms dramatically compared with basic motion detection on a site with palm trees moving in the wind.
• Export that stands up. Check how footage is exported and whether it can be watched without proprietary software. Evidence you cannot hand over is evidence you do not have.
• Offsite copy. A recorder in the room that gets broken into protects nobody. Where it matters, copy critical footage offsite, a subject we cover in our guide to disaster recovery and backup in the UAE.

Security of the recorder itself

A surveillance system is a set of internet capable devices on your network, and recorders are a well known target. Three rules cover most of the risk. Change every default password, on the recorder and on every camera. Put cameras and the recorder on their own VLAN with no route to the business network. Never expose the recorder's web interface to the internet for remote viewing, and use the vendor's proper remote access method or a VPN instead.

A worked starting point

For a Dubai warehouse with 16 cameras at 4 Mbps, 30 days continuous retention and redundancy, you are looking at a 32 channel recorder with input bandwidth above your total stream rate, surveillance rated disks totalling well beyond the 20 terabyte raw figure once redundancy is included, a ventilated location, protected power and a separate VLAN. Switch to event based recording overnight and the disk requirement falls considerably.

Codeeo Tech supplies recorders, cameras and the switching behind them, including Hikvision and D-Link surveillance, to businesses across the UAE. Send us your camera count, bitrate and retention requirement through the contact page and we will do the storage arithmetic with you.

Cover photo: CCTVBrickWall2, via Wikimedia Commons (CC0).