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I am trying to shrink my 300GB partition. There is just 50GB used. So I ran defrag c: /x which should consolidate free space ("Free-space consolidation is useful if you need to shrink a volume, and it can reduce fragmentation of future files.")

After running the defrag command the result was:

Volume Information:
        Volume size                 = 297.57 GB
        Free space                  = 248.53 GB
        Total fragmented space      = 1%
        Largest free space size     = 132.19 GB

Why didn't it create a much larger block of free space? After running the command I was able to shrink the partition to only 170GB despite only 50GB actually being used. Do you suggest some other software utility which can do this better then MS defrag?

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I've tried many tools, starting with defrag C: /X (which tries, but doesn't give good results) and found out these steps give the best results:

  1. Perform an Ultradefrag full optimisation
  2. Perform a MyDefrag Consolidate free space script on the drive.

Note that MyDefrag (formerly named JkDefrag) is not maintained any more but the 4.3.1 version in the WayBack machine still works very well as the underlying defragmentation APIs in Windows haven't changed.

References:

1

Certain system files are not moved by MS defrag and deliberately spread on the disk. You need to use a bootable 3rd party defrag tool to do an offline defragmentation. Just google defrag bootable

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I would like to add to mr James answer that also some parts of NTFS filesystem like Microsoft File Table can be allocated in the middle of the disk. In older defrag MS tools it was visible very well, Windows XP defrag tool for example if I recall correctly or O&O Defrag. I personally have a lot successes with shrinking file systems (even where operating system lays) using gparted. Please note that shrinking large ntfs file systems with gparted may take really long time without any notification except HDD led blinking. Having a backup before every shrinking process is really good idea.

  • I booted from Windows 10 install flash drive. Ran defrag c: /x from c:\windows\system32 (because it is not on the x: from the flash), but it was the same - Could not shrink the volume after this any more :-] – Vitas Jun 5 '15 at 17:50

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