Page Files and Fragmentation

Anytime you're dealing with writing files to and from a hard drive, fragmentation is going to be an issue. After many years of writers pounding away at how performance suffers when a hard drive isn't defragmented, more and more users are making it a part of their regular computer maintenance. Briefly, fragmentation occurs when a file is written to a drive and there isn't sufficient contiguous space on the drive to hold each part of the file in order. When a drive is relatively empty, fragmented files are less likely to occur since there are numerous large blocks of space available. As the drive fills up and files are also deleted, different sized pockets of empty space occur making it more difficult to find larger areas of contiguous space. Defragmenting the drive gathers the pieces of files that weren't able able to be written contiguously and reorders them on the drive. The performance gain is achieved by the hard drive heads not having to move to many different locations on the hard drive platters to gather the pieces of a file when it's accessed.

Paging files are normally created when a drive is relatively empty and finding a large contiguous block of space is not a problem. Refer back to the screen capture above and you'll see that the initial size of the page file is 1152MB. The question becomes, since a page file is created all at once in a contiguous block, why would it ever become fragmented? The answer is because a page file is dynamic. By default, Windows XP creates a pagefile that can be expanded and contracted depending on the amount of extra virtual memory that's needed. If the initial block of drive space that was allocated at setup becomes surrounded by additional files that have been saved to the drive, a fragmented page file can occur when the operating system expands it past the initial size. This is the very reason why having a dedicated drive for the paging file is such an attractive option. It eliminates fragmented page files. Unfortunately, having a dedicated drive is not a common option. To check whether or not the page file is fragmented:

Click [Start] then [Run] and enter compmgmt.msc in the [Open:] line to open Computer Management Console
In the left pane, click [Disk Defragmenter] under the [Storage] section.
In the right pane, click the drive that contains the page file and click [Analyze]

In a few minutes you'll be presented with a dialog box where you can click on [View Report]. Scroll down until you come to the pagefile section. It will tell you the size of the pagefile and the fragmentation status. Great. Just click on defragment and the drive and page file will be defragmented, right? Wrong. The next article in the series talks about defragmentig the page file.

Page File Articles Series

[ Paging File ] [Locating the Page File ] [ Sizing the Page File ] [ Physically Setting Page File Size ]
 [ Page Files and Fragmentation ] [ Defragmenting the Page File ] [ Paging File Performance Monitoring ]