http://aws.amazon.com/storagegateway/ http://aws.amazon.com/storagegateway/ is a little like what you require (if you're unfamiliar). It's not unlimited, but c

http://aws.amazon.com/storagegateway/ http://aws.amazon.com/storagegateway/ is a little like what you require (if you're unfamiliar). It's not unlimited, but currently its 32TB/volume and you're charged for the storage you use, rather than what is provisioned. It supports encryption at rest.