Most advice on CCTV storage starts with a calculator: cameras, resolution, frame rate, out comes a number of terabytes. The arithmetic is fine. The starting point is wrong. The question that actually decides how much storage you need is a much simpler one. How many days could pass between something happening and you realising you need the footage?
Start with the discovery gap, not the terabytes
A recorder keeps footage for a fixed number of days and then begins recording over the oldest material. So the only number that matters is whether that window is longer than the gap between an incident and the moment somebody goes looking for it.
That gap is longer than people expect. A family away for a few weeks over the school holidays finds the damage on the day they get home. A business closed over a long weekend or the Christmas shutdown finds the forced roller door on the first morning back. A neighbour knocks on your door days after their car was broken into, asking whether your cameras caught anything on the street. Police investigating something nearby may make contact well after the event.
In each case, a system that keeps a week of footage has already overwritten the answer. Size the storage to cover your longest realistic absence or shutdown, then add a margin, and work backwards to the drive from there.
What actually fills a drive
Once the number of days is settled, a handful of settings decide how much space each day consumes.
- Resolution and frame rate. Higher of either means more data per second. Many systems record more frames than the scene genuinely needs, and trimming that is one of the easiest gains available.
- Newer codecs such as H.265 can store comparable picture quality in substantially less space than the older H.264, so confirm which one your recorder is actually using rather than assuming.
- Continuous versus event recording. Recording only when motion or a detection event occurs stretches a drive a long way, at the cost of occasionally missing the seconds before a trigger.
- The scene itself. A camera watching a busy road, a tree moving in the wind or a grainy infrared picture at night generates far more data than one watching a still driveway. Night footage is regularly the heaviest part of the day.
Getting these settings right at installation is part of a properly configured security camera system, and it usually matters more than simply buying the largest drive available.
The recorder does not tell you when footage disappears
Overwriting is silent. Nothing flashes, nothing beeps, and nothing warns you that the evening you now care about was replaced by last night’s recording. The moment something happens, export the relevant clip to a phone, a USB stick or a computer before the loop reaches it. Treat that as the first step, ahead of phoning anyone.
Drive failure is silent in much the same way. A recorder can sit with a failed or unformatted drive for months while the live view on your phone looks perfectly normal, because live view does not depend on recording. Checking that playback actually works is a key part of routine CCTV servicing, and it is the check most people have never done.
Not every hard drive belongs in a recorder
A recorder writes to its drive continuously, day and night, from several streams at once. Desktop drives are designed for a very different pattern of use. Surveillance-rated drives are built for constant writing and are the right choice for any system you depend on.
Where the recorder lives matters as well. A recorder shut in a hot cupboard or a Perth garage in summer is asking its drive to work continuously at high temperature, which shortens its life. A little airflow does more for reliability than a bigger drive does.
For businesses, keeping everything forever is not the safe default
It is tempting to assume more retention is always better. For organisations covered by the Privacy Act 1988, that assumption runs into Australian Privacy Principle 11. Recognisable footage of people is personal information; APP 11.1 requires it to be protected, and APP 11.2 requires reasonable steps to destroy or de-identify personal information once it is no longer needed for a permitted purpose. Since late 2024, APP 11.3 has made clear that those steps include both technical and organisational measures.
In practice, that means choosing a retention period for a stated reason, writing it down, and letting the recorder’s automatic overwrite do the destruction. Exported clips need the same discipline, because a folder of saved incidents on a shared computer is still personal information being held. When a recorder is replaced, its old drive should be wiped or physically destroyed rather than left in a storeroom. This sits alongside the wider rules on what WA law allows you to record in the first place.
A sensible way to decide
For a home, cover the longest time you are realistically away plus a margin. For a business, cover the longest closure in the year plus a margin, and document the period and the reason. Then configure the recorder to achieve that, check that playback genuinely works, and put a reminder in the calendar to check it again.
Frequently asked questions
Can I store footage in the cloud instead of on a hard drive?
You can, and some people use both. Cloud storage protects footage if the recorder is stolen or damaged, but it depends on your upload speed and a subscription, and continuous high-resolution recording from several cameras can overwhelm an ordinary home connection. A common arrangement is local recording for everything, with cloud copies of important events only.
Will adding more cameras later reduce how many days I keep?
Yes, unless storage is added at the same time. Every camera shares the same drive, so a system keeping a comfortable number of days with four cameras will keep noticeably fewer with eight. Plan storage for the number of cameras you expect to end up with, not only the number you are starting with.
What happens to recording during a power outage?
Without backup power, recording stops when the power goes out and resumes when it returns, which leaves a gap at precisely the moment some intruders rely on. A small uninterruptible power supply on the recorder and network equipment bridges short outages and allows a clean shutdown during longer ones.
Can I add a second hard drive to my existing recorder?
Often, provided the recorder has a spare drive bay and supports the capacity you want. Many compact recorders have a single bay, in which case the options are a larger replacement drive or a recorder with more bays. Checking the model before buying anything saves a wasted purchase.
We size the drive to how long it takes you to notice
On every camera job, we ask two questions before choosing storage: how long are you ever away, and how long is the business ever closed. Then we set the recording settings to match, confirm playback is actually working before we leave, and show you how to export a clip in under a minute. VG Techs holds Security Licence No. 71264, WA Security Provider 7126 and Master Cabler A045514.
If you are not sure how many days your current system keeps, or whether it is recording at all, call 0472 652 026, email admin@vgtechs.com.au, or book a system check. Based in Piara Waters, servicing greater Perth from Rockingham to Joondalup, Monday to Friday, 8 am to 6 pm.