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System page file on a RAM disk

SoftPerfect RAM Disk does not support storage of page files. Below is a detailed explanation why it is best to avoid placing a page file on a RAM disk or on any other virtual storage device that uses RAM.

What is a page file and how is it used

Page file (swap file, paging file, pagefile or pagefile.sys) is a reserved portion of a hard disk that serves as an extension of physical memory (RAM). When the system runs out of RAM, it moves less-used RAM contents to a page file on the hard disk. The page file is also used for memory dumps, which are system state information records created in case of a crash.

The total amount of memory that can be allocated to all processes in the system is limited by the sum of the size of RAM installed on the computer and the size of the page file.

For example, if you have 4 GB RAM and 2 GB page file, the maximum memory the system can offer would be 6 GB. If you try to run a program that needs 8 GB, it will get out of memory and throw an error. The only two ways to deal with this shortage of memory are either to install more RAM, or to increase the page file size.

What happens if the page file is placed on a RAM disk

Now imagine you put the page file on a RAM disk, i.e. in the physical RAM. Even if you made the RAM disk just big enough to fit the page file and nothing else, it essentially leaves you with 2 GB page file and 2 GB of remaining RAM. By doing this, not only you robbed the system of 2 GB of available RAM, you also left yourself no option to actually extend the page file, because if at some point you do need to extend the page file, you will be trying to extend the RAM by storing the extension on the very RAM you are trying to extend. And, any such extension will be limited by the RAM size (as opposed to a page file on a hard disk, which normally has much more space).

Also, if in this example the system needs 3 GB of RAM, it will be forced to use the page file, even though there is physically enough RAM for that, thus going through unnecessary paging operations.

General advice

  • If you have plenty of RAM and don't use memory dumps, disable the page file altogether. Caveat: some programs, such as Adobe, do not work without a page file; in this case set the minimally allowed page file on the hard disk.
  • If you don't have a lot of RAM and your system does need a page file, place it on the hard disk. If you have two physical disks installed, put the page file on the non-system disk for better performance.
  • If your computer has an SSD, don't use a dynamic size page file to avoid unnecessary disk wear. If it has both SSD and HDD, place the page file on the HDD.

Article details

Article ID: 49

Category: RAM Disk: technical questions and how-to

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