cloud storage gateway

A cloud storage gateway is a hardware- or software-based appliance located on the customer premises that serves as a bridge between local applications and remote cloud-based storage. 

A cloud storage gateway provides basic protocol translation and simple connectivity to allow the incompatible technologies to communicate transparently. The gateway can make cloud storage appear to be a NAS filer, a block storage array, a backup target or even an extension of the application itself.

The gateway may be a stand-alone computing device or a virtual machine (VM) image that provides basic protocol translation and connectivity that allows incompatible technologies to communicate transparently. The need for a bridge between cloud storage systems and enterprise applications arose because of an incompatibility between the protocols used for public cloud technologies and legacy storage systems. Most public cloud providers rely on Internet protocols, usually a RESTful API over HTTP, rather than conventional storage area network (SAN) or network-attached storage (NAS) protocols. 

Many of today's cloud storage gateway products provide data deduplication and compression capabilities to make use of available bandwidth efficiently and move data as quickly as possible. Reducing the digital footprint also lowers cost, because cloud providers charge for over-the-wire transfers as well as for storage space. Other popular features include snapshots and version control, the ability to use local storage as a cache, automated tiered storageand encryption. As the market has evolved, some vendors have dropped the word "gateway" in favor of the word "controller" to emphasize the idea that their gateway products do more than just serve as a bridge.

See also: cloud storage, cloud storage API