Hiberfil.sys in Windows 8 and Why You Should Never Disable Hibernation To Delete It

by windowsiso on October 16, 2012

We explained it before what is hiberfil.sys on Windows 7 computers and how to permanently delete it to free up some hard drive spaces. It’s no longer the case on Windows 8. Why? Because it’s been assigned a special task for a feature that everyone would love and appreciate.

Windows 8 fast boot

Windows 8 introduces a fast, new startup capability that allows Windows 8 to boot much faster than any previous Windows system, including Windows 7. To make this happen, Microsoft optimized the way how normally a Windows machine shuts down. Instead of a full shutdown that basically closes the kernel session, Windows 8 hibernates it to save the kernel session, which is much smaller than a full hibernation, to the disk, more specifically, to the hiberfil.sys file. It makes a faster boot time because resuming the hibernated system session is comparatively less work than doing a full system initialization.

Therefore, unless you deadly need that a few gig space back, you should never disable hibernation on Windows 8. Doing so would result in the permanent removal of the hiberfil.sys file, which would leave no place for the kernel session to be stored, meaning that the fast startup process usage of a saved kernel session would not be possible. You would find your Windows 8 startup takes longer to finish.

How big is hiberfil.sys?

Typically, the hiberfil.sys is sized by default at 75% of physical RAM you have installed on your system. And you can customize the size by running

powercfg /h /size

in Command Prompt as Administrator window.

Powercfg size

How to check if hibernation is on

If the file hiberfil.sys listed from the following command, the hibernation is turned on.

dir c: /ah

check hibernation

To turn off Hibernation

Run the following command in Command Prompt as Administrator:

powercfg /h off

The hiberfil.sys will be removed immediately after it’s run.

To turn back on hibernation

Run the following command in Command Prompt as Administrator:

powercfg /h on

The result is immediate.

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