This is specifically the high capacity storage system. They don’t Experience failures with that. LTT does hype up things as failing but it’s not their essential stuff.

It’s not just them that use these either, there’s also companies like 45 drives

https://www.45drives.com/products/cluster/configure/

You should follow in the steps of Linus Tech Tips and build a massive file server. That’s probably the most comparable system and situation to your case.

Ex

https://m.youtube.com/watch?v=pLC0FUnko-M

https://linustechtips.com/topic/1447503-this-is-my-endgame/

I’d then recommend tape backups that you store off-site , maybe backblaze , but as others stated that might be too expensive.

For 20 TB of computer measured storage you need a 22 TB hdd. ( Due to the way hard drive manufactures market vs how computers read disk size, they use different base systems)

I recently got 20 TB Seagate EXOs for $260 on eBay sold new by Newegg .(20 TB EXOs has 18 TB usable as read by Windows and Linux )