How to have 20-30TB space with many 2TB HDDs?

view story

http://serverfault.com – I want to build a server with a minimum of 20TB - 30TB space. I want to make a single server with many 2TB HDDs. How is it possible to have 20TB-30TB for a single folder ie. /var/www which will contain my server files. It is a web server. (HowTos)