The Virtues of Virtual Memory

Cached 5/28/05 from
http://www.nytimes.com/2005/05/26/technology/circuits/26askk.html
J. D. BIERSDORFER
The Virtues of Virtual Memory
By J.D. BIERSDORFER
Published: May 26, 2005
The Virtues
Of Virtual Memory
Q. What is virtual memory? My Windows XP computer keeps telling me that I am low in virtual memory and I would like to know how to fix it.
A. Modern computers can run many complex programs at once, but may not have enough physical random-access memory - those green and black memory chips plugged into its motherboard - to handle all the tasks at hand. When it runs out of physical memory, the computer turns to its virtual memory to help.

As its name suggests, this virtual memory is not an actual chip on the motherboard, but an amount of disk space on the hard drive that can be used to share the load when the physical memory is full. This virtual memory storage area on the hard drive is often called the page file, or sometimes the swap file.
The physical memory automatically shifts data not currently in use into the virtual memory page file as you work, but there are a few reasons for Windows XP to complain that its virtual memory is too low. The size of the page file is adjustable and may be set too low to accommodate all the tasks you're trying; the page file may be corrupted; or you may not have enough space left on your hard drive for the page file.
If you have plenty of room on your hard drive, try increasing the size of the virtual memory page file in your Windows XP system settings. Right-click on the My Computer icon on the desktop or in the Windows Start menu and select Properties from the pop-up menu. Click the Advanced tab, and in the Performance area, click the Settings button. Click on Advanced in this box and in the Virtual Memory area at the bottom, click the Change button.
In this box, you can set the size for your virtual memory paging file. Microsoft recommends a minimum page file size equivalent to 1.5 times the amount of physical memory, and a maximum equal to 3 times the size of the minimum page file. (For example, if you have 256 megabytes of RAM, select 384 megabytes to 1,152 megabytes of virtual memory.) Instructions for the process and other Windows performance options are in Article No. 308417 in the Knowledge Base at support.microsoft.com.