Archiving Recorded Data

i have a customer requirement to keep recorded data for 24 months. The system has 180 cameras attached, all 1080p recording h265 12FPS. The client is asking for a solution that allows the ability to archive storage older then 6 months then keep it off line to reduce the power requirements of keeping servers online along with the air-conditioning requirements plus maintenance costs on having so many server running 24/7.

is this possible in NX Witness or is anyone aware of a third party software that would allow this to be possible?