Extend your DVR storage by turning on your cameras Digital Noise Reduction (DNR) feature.

A little used feature available on many CCTV cameras these days is digital noise reduction (DNR). Invoking this may significantly reduce the amount of storage required when the camera is put in low-light situations that introduce noise into the picture?
In the sample clips shown below, an extreme low-light situation was simulated by leaving the lens cap on.

The first clip was taken from a MPEG4 NVR and is 1 minute long with no digital noise reduction. The resultant video clip is 36Mb in size due to the noise (snow)!

The second clip was taken from the same NVR and is also 1 minute long but shortly into the recording DNR was turned on. You can instantly see the noise factor improves significantly reducing the overall file size by 30 times! The DNR enabled clip was only 1.2Mb!

If the cameras you use have these features and storage is less than ideal, this maybe a fairly easy fix?