Resolution
The higher the camera resolution, the greater the need for bandwidth and storage space, some common IP camera resolutions are: QCIF, CIF, 2CIF, 4CIF, VGA, SVGA, HD, Full HD and 4K.
Frame Rate
30 FPS is considered real-time motion and shows smooth movement on the recorded video, but if you setup your camera with such frame rate, the use of bandwidth and storage will increase a lot. So for most CCTV projects 15 FPS is enough.
CODEC (compression algorithm)
The choice of the codec dramatically influences the amount of hard disk used for recording, so using modern algorithms like H.264, H.264 plus and H.265 can save more recording space when compared to the old CODEC such as MJPEG or MPEG-4 for example.
Scene activity
If the scene where the camera is installed is very complex, ie there is a lot of movement of people and objects, the need for more bandwidth and storage space will increase.
Continuous or event recording
When you set up a CCTV recorder, you can choose whether videos will be continuously stored even when there are no events in place, or whether the recording will start only when there is an event such as motion detection.