The Three Storage Gateway Types

File Gateway presents a standard NFS or SMB file share to on-premises clients and applications, transparently storing files as objects in an S3 bucket — files written to the share appear as objects in S3, and vice versa, giving file-based applications S3's durability and scale without any application changes.

Volume Gateway presents iSCSI block storage volumes to on-premises servers, appearing as local disks, but backed by EBS snapshots in AWS. Cached mode keeps only frequently-accessed data on the local gateway appliance, with the full dataset safely in AWS (lower on-premises storage footprint, but cache-miss reads depend on network round-trip). Stored mode keeps the entire dataset locally for fastest local access, with AWS holding asynchronously-updated backup snapshots (higher on-premises storage footprint, but no network dependency for normal reads).

Tape Gateway presents a Virtual Tape Library (VTL) interface that existing backup software (expecting to write to physical tape drives and a tape library) can use without modification — virtual tapes are stored in S3, and can be 'ejected' to virtual tape shelves backed by Glacier for long-term, low-cost archival, replicating a traditional tape rotation workflow entirely within AWS.