I'd estimate that Google uses ~1000 TB of fast storage, Bing 500 TB and Yandex 100 TB, so the most basic useful search engine would use at least... 10 TB?
Actually I doubt that this is a true statement and not something to discourage others. Check out these queries:
https://www.google.com/search?q=1 12B results
https://www.google.com/search?q=an 9B results
https://www.google.com/search?q=the 6B results
If we estimate that about half of all English pages contain 'the' or 'an' article we'll have about 15B English pages. If half of all pages contain the '1' then the total number of pages is about 24B. If half of all the pages are in English then the total number of all the pages is 30B. So even the maximum is less than the "hundreds". Similar numbers are at https://www.worldwidewebsize.com/
Ah. I thought that fast storage was a more specific type of storage that might be more expensive. I mean 1000tb is expensive, but it’s feasible to get to that scale with the right funding.