Hello
I have more than 10 year experience in CCTV. According to your post, you want to run some kind of cloud CCTV server, or it will be just reserve copy?
At anyway, you will need to transfer lot amount of data, good be if cameras support FTP, if not- then you need to push RTPS stream, get video from them and then store.
I have some sort of solution for this, please, write me more details!