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On Windows 8 there are the following two files in C:\

  1. pagefile.sys - no surprise. It is as big as I configured as my page file size
  2. swapfile.sys - it is 256MB in size

What is the purpose of this additional swapfile.sys file?

I'm looking for an authoritative answer on this. There is already enough speculation about this on the web.

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The answers here seem fairly authoritative, naming suspend/resume of Metro apps as one main use for swapfile.sys. –  Indrek Oct 4 '12 at 10:21
    
@Indrek yes. I was hoping for a little more detail. Why two files? The existing answers are quite thin on detail. –  usr Oct 4 '12 at 10:46
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Windows 8, oddly enough, supports both swapping and paging at the same time. The pagefile backs overcommitted physical memory and holds objects that haven't been accessed in a very long period of time. The swapfile holds things actively ejected from memory because they won't be accessed for awhile. Paging is more effective on high-performance desktops. Swapping is more effective on low-performance tablets and phones. If one file was used, it would get heavily fragmented because of the mix of small, fixed-size pages for paging and large chunks for swapping. –  David Schwartz Oct 4 '12 at 11:43
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1 Answer

up vote 36 down vote accepted

From a Microsoft staff member at Technet forums.

This is a special type of pagefile used internally by the system to make certain types of paging operations more efficient. It is not related to the automatic dump setting.

 

Suspend/resume of Metro-style apps is one scenario, there could be others in the future.

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