Recording retention depends on:
- frame rate
- codec
- scene activity
- storage space
- resolution
To increase the number of days retention of recordings without increasing the storage space you can reduce the frame rate & resolution of the profile that is being recorded. You can also change the codec from H.264 to H.265. H.265 is a more efficient codec that reduces bandwidth and therefore storage space needed, without reducing quality.
Please be aware that scene activity will impact the retention, a busy scene will require a larger amount of storage compared to a quiet scene.
Camera profiles can be edited here:
The profile you wish to record can be selected here:
On newer NVRs, dual streaming recording can be enabled. This records a lower resolution stream to be used when viewing recordings on a mobile device. This stream is recorded on the same storage space used by the primary stream. It may be a feature you want to disable to ensure the storage space is used for recording one stream only for each camera.
If you do not want this feature, you can disable this feature here:
To calculate the storage space required for your system, you can use Wisenet Toolbox, which is a bandwidth and storage calculator
https://www.hanwhasecurity.com/resources/tools/wisenet-toolbox-plus/
An example of a calculation is shown here: