Final answer:
Data is written to a cached storage layer and asynchronously transferred to Amazon S3 when using storage volumes in Volume Gateways.
Step-by-step explanation:
When using storage volumes in Volume Gateways, data is written to a cached storage layer and asynchronously transferred to Amazon S3.
The cached storage layer is a local disk-based cache that helps improve read and write performance. The data is initially written to this cache and then asynchronously transferred to Amazon S3 in the background.
This allows for faster access to frequently accessed data while also ensuring that a copy of the data is stored securely in Amazon S3 for durability.