Recently, while I was trying to clear off space on the system drive of a client’s server, I found that the file hiberfil.sys (hibernation File) existed there, and was the same size as the page file (which was about 10GB).  I was curious as to why this was there, as any decent system administrator knows that there is no reason to turn on hibernation on a server, as it is never used, and wastes a lot of space.  After a little research, I found that in Windows Server 2008,  hibernation is enabled by default as it is in Vista and 7 to allow for Hybrid Sleep Mode, which is supposed to restore the system in the event of a power failure.  I have not tested how well this works, but I am not sure as to why they would turn this option on by default, as servers are generally protected by a UPS and it uses up valuable hard disk space.  Anyway, here is a quick and easy command to turn it off on Windows Vista, Windows 7, and Server 2008.

powercfg.exe /hibernate off

In the event that you want to turn it back on, here is the command for that.

powercfg.exe /hibernate on

Here is the Microsoft article for this fix.