What is Hiberfil.sys and how do I delete it to save harddisk space?

If you're cleaning your harddisk you'll probably bump into this 1GB - 2GB file which you're not sure what it is..

Well in simple terms it is a file which Windows uses to store all your system data when it goes into hibernation mode. When you wake up from hibernation it will collect data from this file and restore your PC back to the original state :)

If you don't use hibernation mode at all, it's safe to delete the file (saved me 1.5GB of space) by following the procedures below:

Windows XP

This procedure makes use of the graphical user interface.

• Start | Control Panel | Power Options
• Go to the Hibernate Tab.
• Uncheck the Enable Hibernation box if you don't need the hibernation function.
• The file should now be able to be deleted.

Windows Vista / Windows 7

This procedure requires that you be an administrator and uses the command line.

• Start | All Programs | Accessories
• Right click on the Command Prompt entry and choose Run as Administrator from the context menu that pops up (OK any UAC queries about doing this).
• A Command Prompt window should open.
• At the command prompt (where the flashing cursor is) type 'powercfg.exe /hibernate off' and press the Enter key.
• The box should flash and you'll be back at the Command Prompt; type 'exit' and press the Enter key to exit the Command Prompt mode.
• Hibernation should now be turned off and the file HIBERFILE.SYS deleted. If you want to turn it back on repeat the procedure and use/hibernate on instead.