By using the AWS Storage Gateway the S3 Simple Storage Service can be directly accesed by the servers and applications as a local attached storage device. This means that the Gateway can make the S3 buckets to appear just like another local volume.
Recently, the AWS Storage Gateway added a tiering functionality that allow local caching of the frequently accesed files on a local device. This means much lower latency on the locally cached files and the posbility to use new applications on the S3 platform.
The AWS Storage Gateway supports two configurations:
Gateway-Cached Volumes: You can store your primary data in Amazon S3, and retain your frequently accessed data locally. Gateway-Cached volumes provide substantial cost savings on primary storage, minimize the need to scale your storage on-premises, and retain low-latency access to your frequently accessed data.
Gateway-Stored Volumes: In the event you need low-latency access to your entire data set, you can configure your gateway to store your primary data locally, and asynchronously back up point-in-time snapshots of this data to Amazon S3. Gateway-Stored volumes provide durable and inexpensive off-site backups that you can recover locally or from Amazon EC2 if, for example, you need replacement capacity for disaster recovery.
You can take the new Storage Gateway on a test drive for 60 days at http://aws.amazon.com/storagegateway/