You might have several gigabytes of physical memory on your computer, but Windows is always hungry for more. This is specially true with Windows Vista, and the upcoming Windows 7 too demands a fair share though significantly lower than what Vista demands. Soon multi-boot systems with Windows Vista, Windows 7 and Windows XP will be common. I’m sure many are already doing it. In such a setup, assigning disk space for virtual memory for each of these Windows version is such a waste, since only one Windows will be running and using virtual memory at a time.
In order to avoid this and conserve disk space, we can instruct Windows XP, Windows Vista, Windows 7, Windows Server 2003 and Windows Server 2008 to share a same single paging file among all installed instances of the operating system.
To do this, the user first has to decide on which partition the paging file will be located. This partition can be an existing system drive of an operating system or a newly created partition and must be accessible to all the operating systems installed.
Now all you have to do is, move the paging file to this partition and disable paging file for all other drives. Here is how to assign a paging file to a partition.
Go to Control Panel>System. Then click on Advanced system settings (in Windows XP and Windows Server 2003, go to Advanced tab). Click on the Settings button in the Performance section, then go to Advanced tab. Under the Virtual memory section, click on Change button. For all drives that you don’t want pagefile.sys to exist, select them and then set as No paging file to disable paging file on the drive. Select the drive that contains the shared pagefile.sys, set it as Custom size (and enter the value for initial size and maximum size), or simply set System managed size.
Repeat the process for each operating system installed. Remember that the drive letter for pagefile.sys may be different under different booted OS, especially when user installs each operating system on different partition.
Once done, Windows will automatically begin sharing the paging file.
(via My Digital Life)