Volume Gateway is a service that provides cloud-backed iSCSI block storage volumes for on-premises applications. It manages on-premises data in Amazon S3 and operates in two modes: cache mode, where primary data is stored in Amazon S3 with frequently accessed data cached locally, and stored mode, where primary data is stored locally while being backed up to Amazon S3.

In cache mode, your primary data resides in Amazon S3, while frequently accessed data is kept locally for quick access. In stored mode, your primary data is stored locally, allowing for low latency access, while the entire dataset is asynchronously backed up to Amazon S3.

AWS Backup allows you to take point-in-time copies of your volumes in either mode, which are stored as Amazon EBS snapshots. This feature enables you to create space-efficient versioned copies of your volumes for purposes such as data protection, recovery, and migration.