This is a consumer app, so I will care about storage costs - I don't want to have 5x copies of data lying about. The app shards very well, so I can use MySQL and not have scaling issues. Amazon EBS has a nice baseline+snapshot backup capability that uses S3. This should have a light footprint (in terms of storage cost). BUT: the magnolia.com story scares the crap out of me: basically flawless block-level backup of a corrupt DB or filesystem. Is there anything that is nearly as storage efficient as EBS at the MySQL level?