What is the difference between Vista's sleep and hibernate? Sleep awakens quicker than hibernate. In the event of complete power loss, sleep stores the information in RAM, thus loss of power means loss of unsaved data. Hibernate on the other hand, saves the contents of memory to a file called hiberfil.sys, thus you would not lose unsaved data.
The space it takes up depends on your RAM. If you have 1 GB of RAM, Hibernation uses up to 1 GB of hard drive space.If you don't use the Hibernation feature Windows Vista offers, it's taking up a lot of unnecessary hard drive space.
Enable Hibernation in Vista
To enable hibernation, click on your Start menu, and type powercfg.exe /hibernate on
in your search box. Then press Ctrl+Shift+Enter, which will run the command line you typed in as an administrator.
Disable Hibernation in Vista
To disable hibernation, click on your Start menu, and type powercfg.exe /hibernate off
in your search box. Then press Ctrl+Shift+Enter, which will run the command line you typed in as an administrator.