Defragmenting using Defraggler made the fragmentation worse and increases “used space”

defragmentdisk-spacehard drivewindows 8.1

I decided to do a full defragmentation of my C: drive for the first time this day. The defragmenter I use is Defraggler by Piriform. When I analyzed the drive, it detected 13% fragmentation. After that, I clicked the 'Defrag' button to start the defragmentation processes.

I thought it was going fine. At about 50%, it was 10% fragmented now. But then I noticed that the used space increased from 86.3 GB to 103.2 GB! So I stopped the defragmentation. This was surprising.

After stopping it, I decided to analyze the drive again to see if the fragmentation when low. At my surprise, it went HIGH! From that 10% fragmentation, it increased up to 37% fragmented! I was shocked.

I went to Windows' built-in Disk Defragmenter to see if their analysis were the same. At my surprise again, it said 2% fragmented! I was shocked again.

I don't even know which one is accurate now. Defraggler or Disk Defragmenter?!? I don't know which one is the problem. Is it Defraggler or Windows?

Why did defragmenting make the drive more fragmented? Why did the used space increase? Should I try using a different defragmenter? Should I uninstall Defraggler?

OS: Windows 8.1, 64-bit
Defraggler Version: v 2.19.982
C: Drive Capacity: 185 GB

Best Answer

When you stopped Defraggler, it might have left some buffer data behind while it was trying to defragment a very large file.

When you analyzed the drive again with Defraggler, it counted the buffer data as part of the drive as well as all of the fragmented free space (you probably ended up with less contiguous free space after the partial defrag since it was prematurely canceled, so you didn't let Defraggler perform any of its proprietary optimizations).

The best way to resolve the issue is just to run a full defrag again (preferably on boot time), this time without any interruptions.

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