CCTV: How Many Days of Recording? Choosing the Right Hard Drive for Your XVR Recorder

After an incident, the first question is always the same: “did the recorder keep the footage?”. It all depends on the hard drive in your XVR recorder. A drive that is too small overwrites the videos after two or three days, while a properly sized drive keeps several weeks of history. In this guide, we look simply at how many days of CCTV recording you can expect depending on the number of cameras, and how to choose the right capacity.

How the recorder fills the drive

An XVR (or DVR) recorder receives the video stream from each camera and writes it to a SATA hard drive installed inside. Important point: recorders are generally sold without a drive. This is the case for the Dahua recorders in our XVR recorders range, whose product sheets state “drive not included”.

When the drive is full, the recorder automatically deletes the oldest videos to write the new ones (this is the overwrite option). The number of days kept therefore depends on three things:

• The number of cameras: each camera adds its own stream.
• The bitrate of each camera, linked to resolution (2 MP, 5 MP, 4K), frames per second and compression (H.264, H.265, H.265+).
• The recording mode: continuous 24/7, or only on motion detection.

Calculating the number of recording days

Here is a simple method to remember:

1. Volume per day per camera (in GB) ≈ camera bitrate in Mbit/s × 10.8. Example: a camera at 3 Mbit/s produces about 32 GB per day when recording continuously.
2. Total volume per day = that figure × number of cameras.
3. Number of days = usable drive capacity ÷ total volume per day.

Note: a drive sold as “1 TB” shows about 930 GB usable in the recorder's menu. The actual bitrate of your cameras can be seen in the recorder's encoding settings: it is the most reliable value for your calculation.

Which hard drive for how many cameras?

The table below is indicative: it assumes 5 MP cameras in H.265, at about 3 Mbit/s each, recording continuously. With motion-detection recording, the duration is often much longer.

In practice, for a home, aim for at least 7 to 15 days of history: this gives you time to notice a problem after a weekend or a trip. For a shop, a warehouse or a farm, 15 to 30 days is more comfortable.

Our SATA hard drive for DVR / XVR recorders is available in 500 GB, 1 TB, 2 TB, 3 TB, 6 TB and 8 TB, from 200 DH (up-to-date price on the product page). As for recorders, the product sheets for the Dahua 4-channel 5 MP XVR, 8-channel 5 MP XVR and 16-channel 5 MP XVR models list a SATA bay that accepts a drive of up to 16 TB: so you have room to increase the recording time later.

Settings that extend recording time

• Enable H.265 or Smart H.265+ compression: Dahua XVRs in the WizSense range offer it. For the same image, files are much lighter than in H.264.
• Record on motion detection for low-activity cameras (back of the house, garage) and keep continuous recording for the entrance and the street.
• Adjust the frames per second: 12 to 15 frames/s is often enough for surveillance (indicative). Fewer frames means less space.
• Check that automatic overwrite is enabled: otherwise the recorder stops when the drive is full.
• Back up important clips to a USB stick as soon as an incident occurs, before they are overwritten.

Installing and maintaining the hard drive

1. Unplug the recorder before opening the cover.
2. Screw the drive into its slot and connect the SATA cables (data and power).
3. Format the drive from the recorder's Storage menu: it records nothing until this is done.
4. Check the drive's status from time to time in the same menu, and make sure the recorder's clock is correct so you can easily find a sequence.
5. Ventilate the recorder: a device enclosed without airflow heats up, and heat wears out the drive. A wall-mounted rack cabinet from our CCTV accessories range stores and protects everything, as long as air can circulate around it.

For the rest of the installation (cameras, cables, power supply), see our guide installing a CCTV system with an XVR.

Frequently asked questions about CCTV hard drives

Does the XVR recorder come with a hard drive?

No, XVR recorders are supplied without a drive. Add a SATA drive with a capacity suited to your number of cameras and the recording time you want.

Can I use a computer hard drive?

Technically yes if it is SATA, but a recorder writes 24/7. A drive designed for video surveillance handles this workload better. Ask us on WhatsApp for the exact brand and model available for the capacity you choose.

How do I know how many days my recorder keeps?

Open playback and look at the date of the oldest available video: the gap with today is your actual recording time.

Do you deliver everywhere in Morocco?

Yes, Brico MIM delivers to all cities in Morocco, with cash on delivery.