Microsoft Azure Architect Design (AZ-301) Practice Exam

Applying a Read Only caching policy to a SQL Server data disk is optimal for enhancing overall performance, particularly for workloads that involve frequent reads without the need for write operations on the cache layer. In this scenario, SQL Server can benefit significantly from having read operations served directly from the cache, reducing latency when retrieving frequently accessed data.

Read Only caching works by storing frequently read data in the cache, allowing the system to serve read requests from this faster storage instead of the slower disk. Because data being read does not change, this caching method ensures consistency and integrity, which is crucial for database operations.

In this context, while Read/Write caching might seem appealing for scenarios that involve both reading and writing data, it introduces the potential for more complex caching behavior and could lead to increased latency or data integrity issues if not managed correctly. Write Back caching is typically less suitable for database workloads due to the risks associated with delayed writes. None would not provide any performance improvements, which eliminates it as a choice. Thus, Read Only is the best caching policy to apply for improving performance in this scenario.