Practical system guides
CCTV recording & storage planning
Work through retention, bitrate, recording schedules and storage allowance before discussing a CCTV recorder, with a decimal-TB example and a handover checklist.
Define the requirement first
Start with the event you need to investigate, not a drive size. A shop reviewing a weekend incident may need a different retention period from a home checking the previous evening. Write down the required days, who may view footage and how an authorised person requests an export. Retention is a business and privacy decision; do not keep footage indefinitely by default.
Record the site facts
List each camera, its configured average bitrate, codec and daily recording hours. Resolution alone does not determine storage: movement, detail, lighting and compression settings change the data rate. Separate continuous and event-based channels. Event recording can save space but the trigger rate is uncertain; use measured busy-day data and check that relevant activity actually triggers recording.
A practical worked example
For 8 cameras at 4 Mbps, recording 24 hours daily for 14 days: 8 × 4 × 3600 × 24 × 14 ÷ 8 ÷ 1,000,000 = 4.8384 decimal TB. Adding 20% gives about 5.81 TB. The division by 8 converts bits to bytes. This is recorded-data planning, not a promise that a nominal 6 TB drive provides 14 days. Formatting, recorder reserves, redundancy and changing bitrate affect usable capacity.
Safe checks and limits
Ask the installer to confirm supported drive models, maximum capacity, recording throughput and simultaneous playback limits. Do not open a powered recorder or replace a drive yourself. An authorised operator can check the oldest available footage through the normal interface without changing settings. A live picture is not evidence that recording is healthy. Do not overwrite or reset equipment when an incident may require footage preservation.
What to include in a handover or enquiry
Record channel count, bitrate assumptions, recording schedule, target days and allowance alongside the estimate. At handover, request a supervised playback and export demonstration, the actual retention observed after normal use, and an agreed contact for recording faults. Keep exported evidence in an authorised secure location. Use the calculator below to compare assumptions, then share the summary rather than private footage in an initial enquiry.