Fragmentation of system memory is a not-very-widely discussed phenomenon that affects the performance of a computer. However, its negative effects are often overstated, and some of the "cures" offered for this condition can be counterproductive.
Memory defragmentation programs claim to improve the performance of Windows 2000 by forcing the system to swap out all unused pages of memory to disk, and to force all free memory to be contiguous. This way, rather than have this done on demand when launching a program that requires more memory (which can slow down the launching of the program), the garbage collection can be done preemptively or on a scheduled basis. One such defragmentation program is
However, there are some dangers to second-guessing the way virtual memory management works. Servers maintain a balance of memory that favors the programs run by its remote users, not its desktop administrators. Unless you are working with a server that demands a great deal of direct user interaction, memory defragmentation may hurt performance where it really counts with a server—by causing memory that is normally cached in a server for performance's sake to be swapped out to disk.
There are some legitimate reasons for server administrators to be concerned about memory fragmentation. Many clustered programs, for instance, are sometimes unable to work with complete efficiency because of fragmentation – Exchange Server 2000 is one of the most notorious culprits, and is known to not be able to use clustering properly when over a few thousand Exchange objects have been created. Using a memory defragmentation program might offset the problem somewhat, but an administrator should consider other approaches first (such as reducing the number of objects in Exchange if possible, or minimizing the use of other services).
Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter. Check out his Windows 2000 blog at www.thegline.com/win2kblog/ for his latest advice and musings on the world of Windows network administrators – please share your thoughts as well!
This was first published in May 2003