With current 22TB magnetic disks it's less than 20 disks, they would fit into a single machine (4u, likely).
The Storinator XL60 from 45drives (https://www.45drives.com/products/storinator-xl60-configurat...) can hold 60 disks, for (advertised) ~1.4PB of data.
(btw i've learned about 45drives through Linus Tech Tips channel so I think it's obligatory to say LTTSTORE.COM - for the meme)