I'm a security installer, designer, and consultant working out of CO; I've created systems for the largest grows this country has ever seen (30K+ plant counts), and for home grows with only 4 plants. I've worked with all kinds of surveillance tech, from enterprise level on down; perimeter and surveillance systems are my wheelhouse. I was trained to work in this area back in the early 90's by the Department of Justice, when I was installing commercial security systems.
A quick note for anyone looking through this thread-- most posters here are looking at 960H video systems. You should know that these are woefully inadequate for today's needs, and that state of the art is well beyond that, with HD-TVI DVRs recording at 1080p, and cloud storage options on entry level hardware. That 960H image is 960x480 pixels, which was awesome in 2009, but a joke today. If you already have a 960H DVR and lots of cams, an upgrade can cost, but if you buy a new NVR or an HD-TVI DVR, you can record at 1080p (or better) all day long, as long as you have the HD for it. Most of the consumer level combo systems you see are simply trash-- the software is always a joke, no upgrade path, no support, no assurance of security. A decent consumer level system would be from Lorex, which is made by FLIR, who also manufacture Speco, which I would recommend as a prosumer level DVR. Their VT series is HD-TVI, records at 1080p, and has a cloud option that runs on Google drive, and is reliable and simple to use. This solves the problem of thieves stealing hardware, and no need for a hidden HD. Google drive is bombproof, free to start and cheap to upgrade to 1 TB at 10$ monthly, and you have access to your files at all times, as well as those on the local HD in the DVR.
I do not recommend any home camera systems, as these are not appropriate or compliant for a secured commercial facility; I might consider using some of those models in a home grow in a limited way. My home system is a Hikvision NVR with 8 x 3 MP IP cameras running continuously at 2048 x 1536 resolution, which gives me a bit less than two weeks on the 4 TB HD. The level of detail in the video is ridiculous.
