Listen to me. Here is the pro solution. Get yourself something like Fujitsu Eternus cs800 plus Fujitsu lto tape library. Contact sales team and tell them how many data are you going to put there. Result will be all the data available quick if they reside on disk cache, or little bit later if need to be pulled from tape. From your point of view data will be available from mounted network share and transparent in terms of technical magic behind it. Basically - imagine yourself an infinite folder where algorithm is moving data to and from tapes, keeps them healthy, refresh and consolidate when needed. 20 tapes each 12tb plus dedup is like 0.5 PB of data. And you can always duplicate tapes and move to external location. Even if somebody would stole everything from 1st location including hardware, you can get data back.