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About discspace sometimes decreases when using Defraggler

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I found that some in this forum have had the same questions as I did about

Hard Disc usage for C:\System Volume Information and how SVI appear as fragmented (and not defragmentable) space in Defraggler

and the answer is related to how sometimes Defraggler seem to decrease unused disc space instead of incease it.


The short answer is that Defraggler works just fine, but that some files that make up C:\System Volume Information can grow quite large (not caused by Defraggler), appear as fragmented space in Defragglers "graphic display" (and in other defragmentationprograms) and grow in size during defragmentation (at least sometimes).


I do not have the whole answer why this happen.


But if you like to decrease that fragmented space used for System Volume Information,

untouched by defragmentationprograms I do have a sort of solution for you,

by limiting the assigned SVI-space and make more free HD space.


At least for Vista users, but I think the link "Decrease Storage Space Allocated To Systems Restore" below help XP users also.


It started with that I found that 253 GB of my HD (C:) 931 GB was used.

Only knew what 114GB was (using WinDirStat freeware).

This was a problem, 139 GB was invisible for me and I could not tell what that space on my HD really was.

I downloaded and run Defraggler to see if it could determine what the remaining 139GB used disc space was, or free some of it up with defragmentation.


Those 139GB turned out to be 5 hidden files in C:\System Volume Information

They appeared as red=fragmented in Defraggler.

They hade names like:


at that time I could not remove or defragment them.


With further investigation it turned out that those files in C:\System Volume Information are ?System Restore Points? to use if your system crashes. Then you can recreate your system to an earlier state and everything will work fine again (see links below).


Microsoft grant this "System Volume Information"-backup system 15% of system HD space in Vista and 12% in Windows XP.

These hidden 139 GB was the same as those 15% HD space dedicated to System Volume Information (=0,15*931GB)

There is no need for defragmentation programs to defragment these files since they will probably never be used and do not slow your system down that much where they are anyway.

I tried Vista defrag, Defraggler and 2 more defrag programs and none of them did anything about these 139 GB.


However, in Vista you can take away older ?System Restore Points? and free some space, so I did this and freed up some 95 GB of those 139GB used in C:\System Volume Information.


Now some 160GB of 931 GB of total disc space was used.

C:\System Volume Information still used some 44GB of those 160 GB but they appeared now for some reason as blue=not fragmented (Now, since they were blue Defraggler did not really tell me that 44 GB was still used for System Volume Information, but I still knew what they were since they were located at the same place as before in Defragglers graphic display).

44 GB was not perfect, but it was better than 139GB.


But next time when I run Defraggler, during defragmentation process, those 160 GB used space slowly rose to 195GB. :blink:

Somehow running Defraggler, the System Volume Information used or reclaimed some space of those 15% HD space granted by Vista, or maybe it only earmarked some extra 35 GB as used. This change of C: also appeared when I looked at C: in Vista.


Clearly the solution to free up HD space was not to take away some System Restore Points, since all those 15% HD space assigned to C:\System Volume Information could turn from unused to used at any moment.


Anyway those 15% HD space (or 139GB in my case) that Vista dedicates to C:\System Volume Information is far to much to use for restore points.

(really, I could spare that space, but when used HD space deviates between 100GB and 250 GB from day to day and WinDirStat can't tell me whats on my Hard Drive, I get nervous)


I found some links that helped me limit size dedicated to "C:\System Volume Information" :


Decrease Storage Space Allocated To Systems Restore


Reclaiming disk space from ?system volume information?


I limited System Volume Information to 4 GB and now disc usage does not increase when using defraggler anymore.


To do this I opened the Command Prompt (with admin privilegies) and wrote:

C:\Windows\system32>vssadmin Resize ShadowStorage /For=C: /On=C: /MaxSize=4GB





  • Disc usage does not increase when using defraggler anymore.
  • I have more disc space since only 118 GB is used (=114+4).
  • I freed 134 GB HD space.
  • It is easier to know whats on my HD. SVI size are between 0 and 4 GB.
    (also, with the "Command Promt command": vssadmin list shadowstorage one can see exact used SVI space at the moment.)



And the small risk is of course that you might set this size too small and don?t have the restore point you like when you need it.

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Hi Slatibartfast, and welcome to the forum.


You've obviously gone to a lot of trouble to put this information together, and it's an extremely admirable first post. The size discrepency in Vista has been posted about before, but no one has gone to this length to try and explain the reasons why.


I have no experience with Vista, although I have reduced the amount of C:\ System Restore disk allocation on my XP machine via System Restore settings.


For the benefit of those who may not know, that is "Right Click My Computer\Properties\System Restore Tab\Settings".


Again, thanks for taking the time to post this.


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