Well, there are also data integrity issues to take into account... in the simplest terms, you'd actually need 3x the available storage to "guarantee" that there won't be any bit nor data loss if a single drive (our of three) - does... Add a potential (mandatory?) off-site backup, means of restoring it, and... Not even getting into the bandwidth cost can of worms.

Again, this is in very simple (and low-scale) terms.