The file system cache is an area of physical memory reserved for frequently and repeatedly used file system data (it does not store code pages). This cache is maintained by the Windows NT Cache Manager for use by all processes. Processes map or copy files into the cache, depending on how they will use the files. If a process finds a page it needs in the cache, it can avoid costly disk I/O.
Servers running Internet Information Server are well suited to take advantage of the performance gains provided by the cache. Therefore, it is important that you provide enough physical memory to the server to allow the operating system to maintain the cache at an optimal size.
This section explains how Internet Information Server uses the file system cache, how to monitor the size and efficiency of the cache, and how to interpret the data you collect.