Codec/Hardware Advice on real-time encoding multiple HD streams
To do this, you would need real time encoding hardware and some seriously high speed hard drives.  I know devices like the Matrox MX-02 will work for 1080p30, but I'm not sure about resolutions higher than that and at 60p.  I think Black Magic Design has some 4k real time encoders but I'm not sure if they support 60p.  Multiple SSDs would also pretty much be a requirement.  Probably on separate controllers and even then the bus rate might be a bottleneck with that much data.