How to Handle the Gigantic hiberfil.sys in Windows

You might have came across a gigantic file in your PC’s system drive named “hiberfil.sys.” If you are thinking of deleting it to gain some space, think twice. Hiberfil.sys is a very important system file that is used for writing processes stored in the memory, similar to what pagefile.sys does. But what are those processes and what happens if you delete the hiberfil.sys? Let’s find out in this article.

Windows hibernate mode uses hiberfil.sys to store the running processes. Hibernate is a power saver feature of Windows that allows Windows to save all of your current session to the hard disk before shutting own the PC. On your next boot up, Windows will restore the session from the hard disk so you can continue your work from where you stopped previously.

The hiberfil.sys file is where Windows stores the current session. Most of the time it will be close to the size of your system’s RAM (75% of the RAM size by default) since the saving process requires moving the session from the RAM to the hard disk.

As you may have guessed, if you delete the hiberfil.sys file you will not be able to use the Hibernate feature of Windows. The Hibernate option will be removed from the power options. On top of that you will not be able to take advantage of the Windows 10 fast startup feature that takes advantage of hiberfil.sys file.

It may be a bad idea to delete hiberfil.sys, but deleting it is also an enticing option. hiberfil.sys is a huge file with a default size of 75% of your actual RAM. Therefore, if you have 16GB RAM, it will take up to 12GB of space on your hard disk for the hibernate feature.

If you never use the Hibernate option or can carry on without it, then deleting hiberfil.sys to gain some space could be a good option.

You need to open an elevated command prompt window to run the command to turn off Hibernate. There are many ways to do this, but an easier option that works in all Windows versions is to simply type cmd in the search box, and right-click on the Command Prompt from the search results. From the menu, click on “Run as administrator” and confirm the prompt to open an elevated command prompt window.

Type the following command in the command prompt

powercfg -h off

and hit Enter. There will be no confirmation, but you will be able to see an increase in disk space in your system drive.

What-is-hiberfil.sys-Disable-hibernate

If you are not comfortable with the changes, you can re-enable the Hibernate feature by typing the following command in the command prompt:

powercfg -h on

What-is-hiberfil.sys-Enable-hibernate

Unfortunately, you cannot move hiberfil.sys to another partition or external drive, unlike pagefile.sys. However, you can resize it to a smaller size to free up some hard disk space. This will only apply if you don’t use RAM too extensively. If the size of processes in the RAM exceed hiberfil.sys’ file size, it will lead to Hibernate mode not working, and you may also lose the current session.

To resize hiberfil.sys, open an elevated command prompt window again and enter the following command:

Powercfg –h –size (size in percentage)

Replace “size in percentage” with the actual size you want the file to be. By default it is 75% of the actual RAM, so you need to choose a percentage below that, but you can’t go below the 50% threshold. For example, you can set it to 55% by entering the command:

Powercfg –h –size 55

What-is-hiberfil.sys-resize-hiberfil.sys

Depending on whether you are using the Hibernate feature, you might want to retain or delete the hiberfil.sys file. And if you want the best of both worlds, you can resize hiberfil.sys to gain some storage space and still keep using the Hibernate feature. How are you planning to handle hiberfil.sys? Do let us know in the comments.

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