The strange case of the bloated C:WindowsCSC folder


A few days ago, when I was working at the office on the corporate network, I had to access a network share containing some installation files. At the time of starting this process, I remember distinctly that my disk free space was around 25GB or thereabouts. A few hours later, I found that my disk free space was down to almost 1GB! This, despite the fact that I never installed anything actually – I had just visited the network share to inspect file details.

A scan of the system with TreeSize Free (there are many others like SequoiaView which I have used as well) revealed around 25GB in the C:\Windows\CSC folder itself. On first thoughts I was wondering if this folder was some kind of C# compiler related folder but that was quickly ruled out.

The answer is that this folder is used by the Offline Files feature in Windows. The way to check on the status and configuration for Offline Files in Windows 8.1 is quite simple. Open the Control Panel, and do a search for the keyword ‘Offline’. You will see the entry under ‘Sync Center’:

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Click on ‘Manage offline files’ and therein you can check if Offline Files is enabled:

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Then you can click on ‘Disk Usage’ to actually check how much space is used by Offline files. There are some files which are temporary in nature, and as you can see below, that was the case in my scenario. My colleague, Sujay Desai gave me this link to help understand what the Temporary Files really meant.

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A good way to mitigate and control the disk space for Offline files is to adjust the limit of disk space for this feature. But I first chose to delete the ‘Temporary files’. That takes a few minutes typically and it will report that it has deleted the same:

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Now, if you are a travelling person, you must also be aware of a proactive feature wherein on a slow connection Windows will automatically start caching files using Offline files. This is not configurable from the UI and can only be controlled by using a Group Policy.

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There are many valid and useful cases where Offline Files can be helpful, but in my case I have no use for it. So, I decided to explicitly turn this Offline files feature off. You will be prompted for a reboot of the system after this is done:

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Disclaimer: please only disable Offline files if you know what you are doing and if it is causing space issues on your boot volume. If you have made offline changes to your files, make sure you sync them back before doing any changes, because otherwise you may lose your changes. So please be VERY CAREFUL when you do this.

The end state in my system is as follows; Offline Files is disabled and the Cache has been emptied:

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And of course, my free disk space is back to normal!

Hope you liked this tip, and if you liked it, please leave a comment and / or rate the blog post. I would appreciate that very much!

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