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© J.C. Kessels 2009

How do I defragment "C:\hiberfil.sys"?

This huge file is used by the hibernation facility and cannot be defragmented on a running system. You can only delete the file, like this:
Windows Vista:
  1. Click Start -> All Programs -> Accessories, right click on "Command Prompt", and then click "Run as Administrator". If User Account Control (UAC) asks you for permission, permit the Command Prompt to run.
  2. Enter "powercfg -h off" (without the quotes).
  3. Reboot. The "hiberfil.sys" file will be automatically deleted.
  4. Repeat point 1 to open a command prompt.
  5. Enter "powercfg -h on" (without the quotes).
  6. Reboot.
Windows XP:
  1. Open the Control Panel
  2. Double-click Power Options
  3. Click the Hibernate tab, de-select the "Enable hibernate support" check box, and then click Apply.
  4. Reboot. The "hiberfil.sys" file will be automatically deleted.
  5. Go to the Windows Help & Support Center and search for "enable hibernation". It should be the first result. The instructions detail some other steps you may need to follow to reactivate the hibernation.
  • Do not hibernate your computer, boot with something else (such as BartPE), and then change the hibernated disk in any way. This will corrupt the disk, a known hibernation problem. MyDefrag contains a test and will refuse to process hibernated disks.

See also:

*  Frequently Asked Questions