In terms of hibernation Windows 8 is no different than Windows 7 or any previous predecessors. Upon installing Windows 8, by default, Windows will allocate an equivalent amount of your system’s RAM to it’s disk. If you look close you will find a file named hiberfil.sys in your root system partition. The size of the hiberfil.sys is the size of your memory, if you never plan to put your computer into hibernation than it’s probably a good idea to disable and gain all the disk space back.
How To Disable Hibernation or Delete the hiberfil.sys In Windows 8
Go to Start Menu and type cmd > right click > Run as Administrator (on the bottom of the menu)
powercfg –h off
Press enter and there you go. You’ve now disabled hibernation in Windows 8 as well as gained some valuable disk space in your main partition drive.
If you are still curious about how hibernation works, Hibernate mode is not sleep mode. When hibernating your computer completely shuts down, however, under sleep mode your PC is not completely shut down; it still consumes a small amount of power.
This method works same across all previous Windows as well. Give it a try if you want to gain some disk space on your main OS partition.
[updated on Nov. 21, 2012]
As matter of fact, hibernation is a lot more important than any previous Windows, and you should never disable it unless the space you saved is very critical to your day to day computing. Here is why.