I wonder how many yottabytes of storage there was in 1800 HD's?
Well, unless each disk had a zettabyte of storage or so, I suspect it was much less than one yottabyte.
Since these were discarded hard disks, I'd assume they averaged in the range of a hundreds of gigabytes, or maybe much less, depending on when they were discarded.
Maybe a nano-yottabyte? A few hundred pico-yottabytes?