• The Storage Gateway service can either be a physical device or a VM image downloaded onto a host in an on-prem data center. It acts as a bridge to send or receive data from AWS.
• Storage Gateway can sit on top of VMWare’s ESXi hypervisor for Linux machines and Microsoft’s Hyper-V hypervisor for Windows machines.
• Relevant file information passing through Storage Gateway like file ownership, permissions, timestamps, etc. are stored as metadata for the objects that they belong to. Once these file details are stored in S3, they can be managed natively. This mean all S3 features like versioning, lifecycle management, bucket policies, cross region replication, etc. can be applied as a part of Storage Gateway.
• Applications interfacing with AWS over the Volume Gateway is done over the iSCSI block protocol. Data written to these volumes can be asynchronously backed up into AWS Elastic Block Store (EBS) as point-in-time snapshots of the volumes’ content. These kind of snapshots act as incremental backups that capture only changed state similar to a pull request in Git. Further, all snapshots are compressed to reduce storage costs.

• • In the following diagram of a Stored Volume architecture, data is served to the user from the Storage Area Network, Network Attached, or Direct Attached Storage within your data center. S3 exists just as a secure and reliable backup.
• • In the following diagram of a Cached Volume architecture, the most frequently accessed data is served to the user from the Storage Area Network, Network Attached, or Direct Attached Storage within your data center. S3 serves the rest of the data from AWS.