Friday, March 8, 2013

Concept Of Windows Page File

Windows system uses a page file to store data that cant be held by your computers RAM when it fills up. While you can tweak the page file settings, Windows can manage the page file fine on its own.  We can see it as the cause of slowdown of tasks, because it is slower to use the page file than your computers RAM, but having a page file is better than not having one.

 Fig1: Page Files

How the Page File Works

The page file, also known as the swap file, page file, or paging file, is a file on your hard drive. Its located at C:\pagefile.sys by default, but you wont see it unless you tell Windows Explorer not to hide protected operating system files.

Fig2: Page File Location
Your computer stores files, programs, and other data youre using in your RAM (random access memory) because its much faster to read from RAM than to read from a hard drive. For example, when you open Firefox, Firefoxs program files are read from your hard drive and placed into your RAM. The computer uses the copies in RAM rather than repeatedly reading the same files from your hard drive. Programs store the data theyre working with here. When you view a web page, the web page is downloaded and stored in your RAM. When you watch a YouTube video, the video is held in your RAM. 

Fig3: Hard Dive

When your RAM becomes full, Windows moves some of the data from your RAM back to your hard drive, placing it in the page file. This file is a form of virtual memory. While writing this data to your hard disk and reading it back later is much slower than using RAM. Its back-up memoryrather than throwing potentially important data away or having programs crash, the data is stored on your hard drive.

Windows will try to move data you arent using to the page file. For example, if youve had a program minimized for a long time and it isnt doing anything, its data may be moved to RAM. If you maximize the program later and notice that it takes a while to come back instead of instantly snapping to life, its being swapped back in from your page file. Youll see your computers hard disk light blinking as this happens.

With enough RAM in modern computers, the average users computer shouldnt normally use the page file in normal computer use. If you do see your hard drive start to grind away and programs start to slow down when you have a large amount open, thats an indication that your computer is using the page fileyou can speed things up by adding more RAM. You can also try freeing up memoryfor example, by getting rid of useless programs running in the background.

Myth: Disabling the Page File Improves Performance

Some people will tell you that you should disable the page file to speed up your computer. The thinking goes like this: the page file is slower than RAM, and if you have enough RAM, Windows will use the page file when it should be using RAM, slowing down your computer. People have tested this theory and found that, while Windows can run without a page file if you have a large amount of RAM, theres no performance benefit to disabling the page file. However, disabling the page file can result in some bad things. If programs start to use up all your available memory, theyll start crashing instead of being swapped out of the RAM into your page file. This can also cause problems when running software that requires a large amount of memory, such as virtual machines. Some programs may even refuse to run.

Managing the Page File

Windows automatically manages the page files settings for you. However, if you want to adjust your page file settings, you can do so from the Advanced System Settings window. Click Start -> type Advanced System Settings into the Start menu -> press Enter to open it.


Fig4: Advanced Setting Options

  Click the Settings button under performance. 

Fig5: System Properties

Click over to the advanced tab and click the Change button in the Virtual memory section.

Fig6: Performance Setting Options

Windows automatically manages your page file settings by default. Most users should leave these settings alone and allow Windows to make the best decision for you.


Fig7: Virtual Memory Setting Options
However, one tweak that may help in some situations is moving the page file to another drive. If you have two separate hard drives in your computer, assuming one is the system drive with your programs installed on it and one is a less-used data drive, moving the page file to the data drive can potentially offer some increased performance when your page file is in-use. Assuming that Windows will already be using the system drive if it needs to use the page file, this spreads out the hard drive activity instead of concentrating it on one drive.