I assumed people did not need to be explicitly reminded that you had to provision additional capacity for redundancy, and that you can use different layers of caching (ssd caches, ram caches etc).

And by the way, it was just posted today that you can get 60TB pci gen5 SSDs from Micron: https://news.ycombinator.com/item?id=42122434 : you can still fit all that dataset in a single machine and provide all the iops you need. You'd need just 7 of those.

So yeah, 400TB of data is not much data nowadays.