A cloud controller is a storage appliance that automatically moves data from on-premises storage to cloud storage.
Cloud controllers use hard disk drives, solid-state drives or a combination of the two to store data on-premises. Most of the data held on-premise is cached for high performance, while less-frequently accessed data is moved to the cloud.
According to industry analysts, the difference between cloud controllers and cloud storage gateways is that controllers provide additional storage features such as deduplication or snapshots, while gateways work primarily as an on-ramp to cloud storage.
Examples of cloud controller products include Panzura Cloud Controller, Nasuni Cloud NAS and EMC-owned TwinStrata CloudArray.