CCTV storage requirements depend on camera count, resolution, frame rate, compression, scene activity and retention period.
Retention
Define how many days of footage must be retained and whether different areas need different retention periods.
Capacity
Calculate storage from camera bitrate, retention and recording schedule, then include operational headroom.
Network
Camera traffic, NVR connectivity and management traffic should be considered during network design, especially for large deployments.
This article is general technical guidance. Actual architecture should be validated against the organization's requirements, risk profile and existing infrastructure.