How recording storage works
The recorder writes footage to a hard drive. When the drive fills, it starts recording over the oldest material. That means your retention period is fixed by the drive size, the number of cameras, the resolution and whether you record continuously or only on motion.
Nothing warns you. The system looks the same whether it holds a month or three days.
How long people actually need
For a home, a couple of weeks is usually enough. Most incidents at a house are noticed quickly, either the same day or within a few days.
For a business, longer. Stock discrepancies, cash issues and staff matters often come to light weeks after they happened, during a stock count or an audit. A month is a reasonable working minimum, and some businesses need more.
For businesses with regulatory requirements, there may be a specified minimum, which should be confirmed with the relevant authority.
What eats storage
Camera count is the obvious one. Twice the cameras, half the retention on the same drive.
Resolution matters more than people expect. 4K footage takes far more space than HD. Fitting 4K everywhere and then keeping the standard drive can cut retention drastically.
Continuous versus motion recording makes a large difference. Motion-only recording extends retention considerably, though it can miss things if detection is set poorly, and there is a trade-off in reliability.
The mistake that catches people out
The common story is this. Something happens. It is discovered three weeks later. The owner goes to the recorder and finds that footage from that date no longer exists.
The system worked correctly. It simply was never sized for the time period the business needed. This is one of the most frequent problems we are called about, and by then it is too late.
Getting it sized right
Work backwards from the question: how long could pass before I would realise I need footage from a particular day? Then size the storage for that, with margin.
Tell us how far back you may need to look. We use that requirement, together with the camera count and recording settings, to propose suitable storage.
If your current system does not hold enough
This is usually fixable without replacing the system. A larger drive, or adjusting recording settings, will often extend retention substantially. We can check what your existing recorder supports.