Storage Gateways are physical or virtual devices that provide connectivity to cloud-based storage. While storage gateways are not essential for connection to the cloud, they can improve performance to cloud storage, increase reliability and resilience, reduce the bandwidth requirement by incorporating data reduction techniques like compression or deduplication and can add additional security features for cloud connectivity.
Physical storage gateways contain internal storage capacity, which acts as another storage tier/cache, i.e. data that is more frequently accessed can be accessed locally on the gateway instead of having to be retrieved from cloud storage. Using a virtual appliance provides the same functionality, but local storage which is allocated to the virtual machine is used instead. Considering that this is not yet a significantly sized market, there is a surprising variety of storage gateway vendors.
Common uses for Storage Gateways are for:
– Access to cloud storage as a lower storage tier
– Archive data to the cloud
Some shortcomings for most storage gateways are the points of security and recoverability. All storage gateways offer 256-bit SSL encryption. With entry level devices and especially virtual appliances the encryption key may be vendor-supplied, which may not be secure enough for certain sectors like finance or government. In those areas it would be mandatory to choose a vendor that allows the use of a client-supplied and -owned encryption key. However changing this key will pose new challenges, as in most scenarios the stored data will become unreadable with the old key and would need to be re-read and re-written first. While storing data in the cloud is constantly becoming cheaper, retrieval of data is still comparatively expensive. Before choosing a storage gateway appliance the functionality in the security space should be checked with the vendor to ensure that it fits the requirements.
Recoverability is the second area of concern for storage gateways. If the storage gateway fails, no data will be lost, but data will be more difficult to retrieve and may require increased access to cloud storage. Cloud storage and storage gateways do not satisfy mission-critical requirements, but both are a relatively cheap option to store non-critical data safely.
Keep also in mind that accessing any cloud services will require sufficient bandwidth to the chosen cloud provider.