I'm running latest version of Windows 10 on my Surface Pro 4 with i7/16GB/512GB.

Of the 475 GB available space on my SSD, I was using roughly 150GB. All of a sudden, for no reason, I'm now down to a few kilobytes of space. Looks like most of the space is used by the Windows folder where the OS is - see below.

enter image description here

I have the built in virus protection on and it's up-to-date and showing no issues. Any ideavwhat would cause this explosion on HD utilization? Especially stuff going into Windows folder?

UPDATE: This is where my space is going and it keeps growing faster than I can make space for it. What should I do? enter image description here

  • Did you delete it? According to this it's created by the file verification. So likely you might have a defective drive or something messing with your system files?
    – Seth
    Dec 19, 2017 at 7:04
  • IIRC you can delete this file. Though it’s not normal for it to be so large. It means something with Component-Based Servicing (used by Windows Update and whatnot) is wrong. You may have to reinstall Windows anyway.
    – Daniel B
    Dec 19, 2017 at 7:05
  • I deleted one with an older date. There are several of them. The December cumulative update has been failing. It was taking me forever to restart my Surface so I had disabled Windows Update for a few days. Today I re-enabled it so I’m pretty sure this has something to do with it.
    – Sam
    Dec 19, 2017 at 7:08
  • Yes, that’s the issue and looks like this issue has been around for a long time and Microsoft still hasn’t fixed it! answers.microsoft.com/en-us/windows/forum/windows_7-update/…
    – Sam
    Dec 19, 2017 at 7:23
  • The issue is the result of problems while installing updates. Resolve the issue of installing updates and get your system fully patched and the problem will go away. You can delete the CBS.log files. You might need to stop the trusted installer service to delete the main one. The log also contains all the issues and processes that are occurring. You might need to run a dism /cleanup-image /Online to try to resolve your update issues. Dec 19, 2017 at 7:24

2 Answers 2


Your update appears to have provided the answer. CBS.log is a log file for Component Based Servicing, and there seems to be a bug with it that causes it to fill up all available space.

Unlike NBC.log and FOX.log1, you can delete it safely. You may need to take ownership and delete it that way though.

You need to be logged in as an administrator and run Command Prompt as administrator.

Change to the log file folder (cd C:\Windows\Logs\CBS), take ownership of the file (takeown CBS.log), and then delete it (del CBS.log). You can then exit the command prompt. You should then get most of your space back.

1: No such file exists.

  • Ya, it's good to delete big file with del command not with pressing delete key.
    – Biswapriyo
    Dec 19, 2017 at 8:51

In my case, the Windows\Temp folder grew until almost full the Hard disk space, by unknown reason. Using WinDirStat application running like administrator (running like normal user a lot of used space remains hidden) I discovered 200 GB of files in the Temp folder. I opened a Command prompt like Administrator and executed inside the C:\Windows\Temp the risky operation

del *.*

That recovered a lot of space and Windows doesn't seems to be affected.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.