In Windows 8 and Windows 10, there is a feature called Fast Startup to speed up the boot process. When enabled, it makes Windows boot very fast. The operating system uses a hybrid shutdown which writes the memory occupied by the OS kernel and loaded drivers to the C:\hiberfil.sys file. Unlike full hibernation, it discards the user session by logging out the user. On the next boot, it restores the saved information to RAM immediately but loads a fresh user session. In this article, we'll see how to disable full hibernation to save disk space but keep fast startup.
When you disable hibernation completely, it disables the Fast Startup feature too. Obviously, Fast Startup depends on hibernation and cannot work without it.
However, in many cases, users want to disable hibernation to save disk space on the partition where Windows is installed. The hibernation file consumes at least half the amount of disk space even if you compress it. In Windows 10, there is an additional option you can use to save disk space without completely turning off hibernation. We already reviewed the first method in the following article:
An alternative is to change the hibernation type. Thanks to the ability to switch the hibernation type from full to reduced, you can keep the Fast Startup feature turned on but save a considerable amount of disk space by disabling full hibernation. It still keeps the hiberfil.sys but its size is reduced. So Windows 10 supports two hibernation types: Full and Reduced. Here is how you can switch between them.
Disable Hibernation but Keep Fast Startup
Do the following.
- Open an elevated command prompt.
- Type or paste the following command
powercfg /h /type reduced
This command will reduce the hibernation file size for storing only the OS kernel and drivers for Fast Startup.
powercfg /h /type full
Full Hibernation supports storing the state of all opened apps, files, drivers etc - everything is restored as it was. This process is still much faster than a cold start of the operating system. But as mentioned above, it takes at least 40% of the installed memory's space on the drive.
The reduced hibernation type keeps only enough data to store the non-user session (kernel) state. The C:\hiberfil.sys will take only 20% of the installed RAM. It is not possible to use the Hibernate command in the reduced mode, it will disappear from the Start menu and the Power menu in Win + X.
Tip: If you compressed your hibernation file earlier, the powercfg /h /type reduced command can give you an error "The parameter is incorrect".
To avoid this, try to uncompress the hibernation file using this command:
powercfg hibernate size 0
Then run the command to use the reduced hibernation file.
To automate these tasks, you can use Winaero Tweaker. The approprite GUI can be found under Behavior\Hibernation.
You can download Winaero Tweaker here: