The file cache is built into both Windows 2000 Professional and Server, and it functions identically in either environment. Caching is everywhere! An interesting aspect of the Windows 2000 file cache stems from this ubiquity. When Windows 2000 Server file servers are accessed by Windows 2000 Professional clients, files accessed across the network are subject to memory-resident caching on both the server and the client side! With caching everywhere, frequently accessed files are likely to be resident in memory on multiple machines. From one standpoint, this leads to duplication and adds to the memory requirements of Windows 2000 machines. On the other hand, all this file caching is very effective from a performance standpoint, so there is an overall benefit.
On systems configured to run as file servers or Internet web servers, for example, one of the major consumers of real memory is the file cache. Since even large-scale PC servers generally have limited I/O bandwidth compared to enterprise-scale servers, configuring an adequate amount of memory for use as a file cache is important. You should consider that any memory-resident disk cache is an explicit trade-off of memory for disk activity. Normally, in PC workstations and servers, this trade-off yields significant performance benefits. When we discuss disk I/O performance in the next three chapters, we quantify the performance benefit of cache versus disk access more definitively.