If I have the NVR with a lot of storage for historical purposes, I suppose I could have less storage on the BI PC since I figure most event analysis would be within a short time frame. Does that strategy make sense?Nope, BI cannot access NVR storage. In fact the video files are different as well.
To extend this conversation, I have my cameras on a separate network. All of the cameras are connected to POE switches. The BI is plugged into the switch. A dual NIC allows me to also plug the BI into the main network. If I want to add an NVR for testing and backup purposes, I should be able to plug it into the POE switch, even if the NVR has POE, and see all of the cameras on the network. I believe that should allow me to record all of the cameras on both devices. If all the cameras are set to continuously record on both devices, would that cause a problem? Does the POE built into the NVR act as a switch? In other words, can I plug the NVR into the main network and plug one of the NVR POE ports into the camera network and see all of the cameras, effectively making the NVR a dual NIC device? Or does each NVR POE port only see one camera per port?
In theory the POE port on the NVR can only accept one camera. Doesn't mean some units can't accept some, but you wouldn't want to count on it seeing all your cameras.
Best practice is to plug the camera switch into the WAN/LAN of the NVR.
By design, the POE ports on the back of the NVR on most NVRs are assigned its own IP subnet, so in a sense the NVR does act as a firewall/router/dual NIC.
In your situation, if you don't want to plug the NVR into the camera switch, then you either get an NVR with two WAN/LAN ports to do what you want or put all the cameras on the NVR POE ports and then feed the NVR into BI.