Disabling the prefetch and superfetch features avoids some I/O operations to the file system and can reduce the growth of an instant clone's or a View Composer linked clone's virtual disk.

To disable the prefetch and superfetch features, you must edit a Windows registry key and disable the Prefetch service on the virtual machine.

The following steps apply to Windows 7 and Windows 8. The steps might vary on different Windows operating systems.


See the Microsoft TechNet Web site for information on how to use the Windows Registry Editor.


  1. Start the Windows Registry Editor on the local Windows virtual machine.
  2. Navigate to the registry key called PrefetchParameters.
    The registry key is located in the following path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters.
  3. Set the EnablePrefetcher and EnableSuperfetch values to 0.
  4. Click Start > Control Panel > System and Security > Administrative Tools.
  5. Select Services and click Open.
  6. Double-click the Superfetch service.
  7. In the Superfetch Properties (Local Computer) dialog, click Stop.
  8. In the Startup type menu, select Disabled.
  9. Click OK.