Understanding Cache, Non-Cache, and Paging Read/Write Operations
If you are developing a file system filter driver—whether for data protection, continuous data protection (CDP), auditing, or encryption—understanding how Windows handles file Input/Output (I/O) is absolutely critical. When an application reads or writes to a file, the request doesn't always go straight to the hard drive. Windows uses a complex architecture involving the Cache Manager, the Memory Manager, and the File System to optimize performance. As a result, a single file operation can trigger multiple different types of I/O requests. In this post, we will break down the differences between Cache Read/Write, Non-Cache Read/Write, and Paging I/O Read/Write, and explain exactly how to intercept and handle them using the EaseFilter File Monitor SDK and File Control SDK . 1. The Core Component: The Windows Cache Manager Before diving into the specific I/O types, it is important to understand the role of the Windows Cache Manager. To speed up file access, Windows attempt...