Today at work I was doing moving some files around when I realized that my C: drive, which has Windows XP on it, was running seriously low on disk space. A quick perusal of the drive uncovered a 1.5 gigabyte file called hiberfil.sys. Given that I never use the hibernation system in Windows I figured this was a prime target for purging, but the system wouldn't let me delete the file as it was locked by the system that controls hibernation. So, off a googling I went and found my answer on the very first result. Read on for a quick explanation.

Microsoft added the hibernation system to Windows a few years back and in many situations it can work great. The whole idea of hibernation is to let you freeze the computer as it is, with all the software running, and be able to turn off the power, then when you want to you can just turn on the power again and there's your computer ready to go! To do this Windows makes a file in your system drive, usually C:, that is about the same size as the amount of physical RAM your computer has, so if you have 256MB of RAM then your hibernation file, hiberfil.sys, will be 256MB in size, thus if you have 1.5GB of RAM like my work PC has you'll end up with a 1.5GB file! This can work great with slower computers and laptops where you don't want to go through the whole hassle of booting your computer each time you want to use it for a few minutes but on my PCs I tend to only turn it off when I want to specifically turn it off.

So to turn it off you need to do two very simple things. The steps are to go to your control panel's power controls and simply uncheck the "enable hibernation" button, et voila, 1.5GB of space back for me.

In a little bit more detail, there are actually two different routes you need to take depending on how your computer is set up. First off open your control panel, if you have Windows XP set with the default fancy display go to the Start menu and click on Control Panel, whereas if you've enabled the so-called "classic" interface you need to go to Start, then Settings and then Control Panel.

Once the control panel opens you then need to find the power controls. If you've got the categorized view enabled (it says "Pick a category" at the top) then click on Performance and Maintenance (it has a little pie-chart icon beside it) then click Power Options. If you have the traditional "classic" view where all of the icons are displayed simply click on Power Options and you're away with it. When the window opens you need to click on the Hibernate tab and it will look something like this:

Note: I've got a program installed that makes the colors different so your window is probably more blue looking.

When the window opens simply make sure that the Enable hibernation option is unchecked then click OK to save the change and reclaim your disk space. Should you ever want to re-enable hibernation support just go back to the same window and re-enable it. Easy!