Good Question–What Are These Huge Files?

A client of mine sent me the following question:


I saw these files on my C drive, created on July 19:

hiberfil.sys 2,095,252 KB

pagefile.sys 4,190,208 KB

WTF??? Should I be concerned?


This was my reply:

hiberfil.sys is the file created when you hibernate your computer. It is the image created of your system state, and is always big.

pagefile.sys is the area of the hard drive dedicated to transferring data and applications from the hard drive to the system memory or RAM. The bigger this partition the faster things should load and run. In your case this is like an additional 4 GB of RAM on your system.

Nothing to worry about. Also – not a good idea to delete them either.


I was glad he sent me the question before going ahead and deleting the files.   First of all, Windows would have prevented these files from being deleted, but I have seen clients get creative about deleting operating system files like these and leave themselves with an unbootable computer.  It also meant that this client was being vigilant about just what was on his system.

An easy way for anyone to get answers to questions like these is simply to enter your question into Google.  A quick search on hiberfil.sys yielded this helpful article on Wikipedia.  A search on pagefile.sys got us this useful article from the Microsoft Knowledge Base (KB) that tells how to optimize your pagefile to enhance system performance.  I recommend to my students and clients that whenever you get an alert message or virus warning or are unsure about a computer term, Google can be a great way to get an instant answer.

But it is always better to ask, than to be sorry later.


About the Author:

I am a cybersecurity and IT instructor, cybersecurity analyst, pen-tester, trainer, and speaker. I am an owner of the WyzCo Group Inc. In addition to consulting on security products and services, I also conduct security audits, compliance audits, vulnerability assessments and penetration tests. I also teach Cybersecurity Awareness Training classes. I work as an information technology and cybersecurity instructor for several training and certification organizations. I have worked in corporate, military, government, and workforce development training environments I am a frequent speaker at professional conferences such as the Minnesota Bloggers Conference, Secure360 Security Conference in 2016, 2017, 2018, 2019, the (ISC)2 World Congress 2016, and the ISSA International Conference 2017, and many local community organizations, including Chambers of Commerce, SCORE, and several school districts. I have been blogging on cybersecurity since 2006 at

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