Finding out where your disk space is being used

I ran out of disk space on my Windows 8 laptop. This was very strange since I had plenty of free space a week ago and I haven’t done anything that should have consumed this disk space. I freed up a few GB by deleting unused files, but soon again this unused disk space was consumed. Even as I watched and clicked the Refresh-button every 10 seconds, I could see the free disk space steadily decreasing.

Was this some kind of malicious software? Or an application that kept writing to a log file? Or some performance monitoring that I had forgotten to deactivate? I had no clue and I really had to solve this, or my laptop was more or less useless.

I managed to find a free tool, SpaceSniffer, that really helped. It visualizes your disk usage as a Treemap – with an overview and the possibility to “drill down” / zoom into the details of your disk usage by simply double-clicking on an object. This is like a Business Inteligence-tool for analysing your disk usage. However, it still couldn’t find what was causing my problem. Very strangely, the total disk space reported by the tool was much lower than the real capacity of the disk. This was very worrying – I had to continue looking…

I tried another trick. Maybe the tool wasn’t able to investigate all of my folders. I started SpaceSniffer with the “Run as administrator” option in Windows. Suddenly it found all of my disk space!

The culprit was something called “Windows Search service”, that stored an index file that took a terrific amount of space. The description of the service says “Provides content indexing, property caching, and search results for files, e-mail, and other content”. I don’t know if it’s a bug in the Windows Search service or if it’s because of my large amount of emails, but it had generated a file of 70 GB (on my 220 GB disk) and constantly growing! No wonder I was running out of space. The solution was to stop that service and delete the large file.

So my recommendation if you want to find out how your disk space is being used, try SpaceSniffer and run it as administrator.

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2 responses to “Finding out where your disk space is being used

  1. I have been using SpaceSniffer since 3-4 years ago and it’s a must-must have tool. Microsoft should integrate it in Windows Explorer!

    • Agreed! Before finding SpaceSniffer I was actually thinking of visualizing my disk space in Power View. :-) However no need for that when you have SpaceSniffer!