My drive keeps filling up even though I don't have much installed. I checked the disk with WinDirStat and found that a .sys file is using around 30 GB. The file is hiberfil.sys, and this Windows installation is fairly old. Why is it so large, and what can I do to reduce or remove it?
2 Answers
Make sure you’re looking at the exact filename. pagefile.sys is the virtual-memory paging file and can also be quite large, while hiberfil.sys is specifically for hibernation. The two files serve different purposes, so don’t reduce or delete the page file just because hiberfil.sys is taking up space.
hiberfil.sys is the file Windows uses to save your memory contents when you hibernate. Its size is generally related to how much RAM you have, so a large file can be normal. If you don’t need hibernation, open an elevated Command Prompt and run `powercfg.exe /hibernate off`; this removes the file and frees the space. The tradeoff is that hibernation will no longer be available.
That explains it—I use hibernation pretty often, so I’ll probably keep the file rather than disable the feature.