Monitoring and Tuning Your Server
Monitoring and Tuning Your Server |
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The largest “chunk” of activity in Windows 2000 Server is a process. The physical RAM available to a process is called its working set. If the needs of a process exceed the amount of available RAM, that is, if the process is not able to store all of its code and frequently-used data in physical memory, some of the information must be stored elsewhere, usually on disk (as virtual memory). This causes an increase in the amount of disk activity, which slows down the server. Some memory contains information (typically code) that is used often, and it should not be sent off to disk because this will result in serious performance degradation. A memory region of this type is designated as “nonpageable.”
Within each process, Windows 2000 uses threads to accomplish particular tasks. The memory occupied by threads is part of the working set of the process, except for some special threads that run in nonpageable memory. Threads that service connections in IIS 5.0, for example, are not pageable. Sockets also use nonpageable memory. If too many sockets and nonpaged threads are created, the system runs out of nonpaged pool memory and a “bottleneck” occurs. (This can happen, for example, during some forms of denialofservice attack, in which the server is barraged with requests. For more information, see Security in this book.