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Tip: Learn Best Practices for Optimizing the Virtual Memory Configuration


In a default installation, Windows creates the page file in the root folder on the same drive that holds the Windows system files. The size of the page file is determined by the amount of RAM in your system. By default, the minimum size on a 32-bit (x86) system is 1.5 times the amount of physical RAM if physical RAM is less than 1 GB, and equal to the amount of physical RAM plus 300 MB if 1 GB or more is installed. The default maximum size is three times the amount of RAM, regardless of how much physical RAM is installed. On a PC with a processor that supports Physical Address Extension (PAE)—which is to say, on any PC that is capable of running Windows 7—the maximum size of the page file is 16 TB. You can see the page file in a Windows Explorer win¬dow if you configure Windows to show hidden and system files; look for Pagefile.sys in the root of your system drive.

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To see the current configuration of your system’s virtual memory, open the System dialog box in Control Panel and click the Advanced tab. Or, for a handy undocumented shortcut, click Start, type systempropertiesadvanced (with no spaces), and press Enter. Under the Performance heading, click Settings. In the Performance Options dialog box, click the Advanced tab. And under the Virtual Memory heading, click Change.

By default, Windows creates a single page file and manages its size. The Currently Allocated num¬ber near the bottom of the dialog box shows how large the file is. If conditions on your system change (say you run an unusually large assortment of memory-intensive applica¬tions), Windows might increase or even decrease the size of the page file. All this happens without you’re knowing as long as you leave the Automatically Manage Paging File Size For All Drives option selected.

If you don’t want Windows to automatically manage the page file, you have the following options:
  • You can move the page file to a different volume if you have more than one volume.
  • If you have more than one volume, you can establish more than one page file.
  • For any page file, you can choose between System Managed Size and Custom Size.
  • If you choose Custom Size, you can specify an initial size and a maximum size.
  • You can remove a paging file from a volume by selecting the volume and choosing No Paging File. (In fact, you can do this to get rid of all paging files, although doing so is not recommended, even on systems with a lot of RAM.)
Should you get involved in managing the page file? If you have more than one physical disk, moving the page file to a fast drive that doesn’t contain your Windows system files is a good idea. Using multiple page files split over two or more physical disks is an even better idea, because your disk controller can process mul¬tiple requests to read or write data concurrently. But don’t make the mistake of creating two or more page files using multiple volumes on a single physical disk. If, for example, you have a single hard disk that contains volumes C, D, and E, splitting the page file over two or more of these volumes, might actually make your computer run more slowly.

If you are short of hard disk space, you might consider setting a smaller initial page file size. Monitor peak usage levels over time; if the peak is well below the current page file size, you can consider reducing the initial size to save disk space. On the other hand, if you’re not short of disk space, there’s nothing to be gained from doing this and you might occasion¬ally overload your custom settings, thereby degrading the performance of your system.

Should you enlarge your page file? Most users won’t need to do this. But you might want to keep an eye on the green line in the Memory chart on the Overview tab of Resource Monitor. If that line is spiking off the top of the graph a great deal of the time during your normal work, you might consider increasing the maximum size of your page file. (Note that you should disregard page file spikes and disk activity in general that takes place while you’re not actually working. This is likely to be the result of search indexing, defragmentation, or other background processes and does not indicate a problem with your actual work performance.

From the Microsoft Press book Windows 7 Inside Out by Ed Bott, Carl Siechert, and Craig Stinson.
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