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Retention is usually discovered at the worst possible moment — an incident surfaces three weeks late and the footage has already rolled over. Storage is the cheapest part of a system to get right at design and the most expensive to fix afterward.
Concord and Woodbridge are the GTA's construction supply chain — aggregate, steel, millwork, mechanical trades and equipment yards, much of it stored outdoors. CN's MacMillan Yard puts significant rail intermodal traffic through the same area. Outdoor storage of high-value material is the defining characteristic, which makes yard analytics and after-hours monitoring more relevant here than building access control.
Copper, tooling, fuel and equipment held in open yards. Detection at the fence line and talk-down capability matter more than recorded coverage of the building.
One megabit per second of sustained video is 10.8 GB per day. Everything after that is multiplication.
| Scenario | Bitrate per camera | Cameras | Retention | Raw storage |
|---|---|---|---|---|
| Small commercial, H.265 | 4 Mbps | 8 | 30 days | 10.4 TB |
| Warehouse, H.265, 4K at docks | 8 Mbps | 24 | 60 days | 124 TB |
| Construction site, motion only | 6 Mbps | 6 | 90 days | 35 TB |
| Distribution centre, H.264 | 12 Mbps | 48 | 90 days | 560 TB |
Desktop drives are specified for roughly 55 TB of writes a year and for substantial idle time. A surveillance recorder writes continuously from every camera and never idles. Surveillance-rated drives carry far higher annual workload ratings and firmware tuned for streaming writes, where a dropped frame matters more than a retried read. Mixing desktop drives into an array is the most common cause of premature recorder failure we see.
Insurers, agreements with shippers and client contracts frequently specify a minimum retention period, and some carry a duty to preserve footage once an incident is reported. Check what you have already agreed to before choosing a number — it is usually longer than the 14 or 30 days a recorder ships configured for.
Rebuilding a RAID 5 array reads every sector on every remaining drive. On a large array that read volume approaches the published unrecoverable-read-error rate of consumer drives, and a second fault during the rebuild loses the array. Use RAID 6 or RAID 10 above roughly 12 TB — and treat RAID as uptime protection rather than backup. It does nothing about the recorder being stolen, which on a construction site is the realistic threat.
Specified by pixel density, not by megapixels
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Credentials that cannot be copied in a parking lot
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Alarms that mean something, so someone still answers them
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Protection on day one, before there is power or a fence
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Someone watching, not just something recording
Read more →Thirty days covers most operational disputes. Sixty to ninety is common where incidents surface through insurance or a customer complaint weeks later. Check your insurance policy and any shipper or client contract first — a minimum is often already specified there.
On-premise for bulk retention, cloud for the subset that matters. A recorder bolted down on site is still the cheapest way to hold ninety days of 24 cameras, but it can be stolen. Replicating alarm events and door-forced clips off-site covers the one failure mode on-premise alone does not.
It can, and it should not. Twenty-four cameras at 8 Mbps is 192 Mbps of constant traffic. Put cameras on their own VLAN with a controlled route to the recorder, and give the recorder no direct path to the internet.
Copper, tooling, fuel and equipment held in open yards. Detection at the fence line and talk-down capability matter more than recorded coverage of the building. Concord and Woodbridge are the GTA's construction supply chain — aggregate, steel, millwork, mechanical trades and equipment yards, much of it stored outdoors.