Explanation: Structured storage is designed, maintained, and implemented by a cloud service provider as part of a PaaS offering. It is specific to that cloud provider and the way they have opted to implement systems, so special care is required to ensure that applications are not designed in a way that will lock the cloud customer into a specific cloud provider with that dependency. Unstructured storage for auxiliary files would not lock a customer into a specific provider. With volume and object storage, because the cloud customer maintains their own systems with IaaS, moving and replicating to a different cloud provider would be very easy.