Is it the norm for makers of DVRs to advertise the feature of being able to add on storage arrays, and then, without stating such up front, make the compatibility a proprietary interface, so you can only use thier devices?
Most makers offer their own ready made add on storage, which has been configured, and tested throughly to work with their equipment. Most of the expansion I've seen has been SCSI (and now some USB and SATA is starting to appear), which you could probably build a custom add on for. However, the manufacturer would advice against it, because they cannot test every configuration possible, and they won't warrenty any damage that could be caused by some off the wall setup. It's most likely possible (there are only so many interfaces that exist for hard drives), the companies 1: don't want to risk the customer screwing something up by 2: offering a product that may be a bit more than you could buy yourself at newegg, but it has been engineered and tested to work reliably with the product.
There are many ways to use storage for video. You are not mentioning what type of DVR you are using, but it is unlikely that a simple DVR manufacturer would R&D his own complete storage solution. Have you looked at places like
Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.