I am not sure about these, as I am not from the Ruby side. That said I am considering to talk with fibervolt.com / linode.com , to see if they can get this done for me.
NoSQL databases are very new , and the application I am planning to use it (MongoDB) can easily run in multiple terabytes a month, as of today I haven't come across anyone who has used it at that scale. Just FYI..so if this something mission critical, do your due diligence on taking the nosql approach.. I chose it because I had no other choice, as I cannot have a preset schema.