What is the high-speed data storage layer called that stores a subset of data for future requests?

The high-speed data storage layer that stores a subset of data for future requests is known as caching. Caching is a technique used to temporarily store frequently accessed data in a location that can be retrieved more quickly than the original storage source. This improves the speed and efficiency of data retrieval because it reduces the time it takes to access information from slower storage solutions, such as traditional hard drives or databases.

By storing copies of data that are often requested, caching serves as an intermediary, enabling applications or users to retrieve this data faster. It is widely utilized across various operating systems, web applications, and databases to enhance performance.

In contrast, other options refer to different concepts. A Storage Area Network (SAN) is a network designed to provide access to consolidated block-level storage, primarily utilized in enterprise environments for storage efficiency and redundancy. A Data Warehouse is a centralized repository that allows for the storage, analysis, and reporting of large amounts of historical data, generally used for business intelligence purposes. Buffering refers to the temporary storage of data while it is being transferred or processed, but it is not specifically focused on future retrieval of requested data in the same way caching is.