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System drive, OS is Windows 7 x64 SP1 Ultimate.

  • Windows Explorer shows 100GB of used space.

  • TreeSizeFree shows 75GB of used space.

  • Total Commander and FAR confirm TreeSizeFree's measurements (counting hidden files).

  • Shadow copy is using up to 5GB with the current usage of 1.36GB.

  • Running FAR from Win7 PE shows the same.

  • Checkdisk shows no bad sectors. Disk is an OCZ SSD.

  • SMART monitor suggests SSD condition is perfect.

Where is the rest of space gone?

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How are you getting the amount of space used via Explorer? From the properties of the drive itself, or selecting all your folders and getting the properties? –  afrazier Oct 11 '11 at 16:15
    
Is this 100GB used space or space on disk? They are two different numbers –  surfasb Oct 11 '11 at 17:21
    
Right click on the drive -> Properties. Used space = 100GB. Capacity = 111GB. –  Neolisk Oct 11 '11 at 17:37
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migrated from stackoverflow.com Oct 11 '11 at 15:35

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3 Answers

up vote 1 down vote accepted

Most Likely Problem: There's a large number of directories and files that even Administrator accounts do not normally have access to, especially in the ProgramData and Windows trees. Without doing something special, most space analysis programs aren't going to correctly account for the space they're using.

Using space analysis programs on the Windows folder is already fraught with problems anyway. The folders are densely hardlinked, and very few programs (including Explorer itself) can correctly handle that. In fact, the only one I know of offhand is Sysinternals' du.exe tool, when passed the -u flag.

If you want to know how much space is really used/free, check the properties of the drive itself with Explorer. Trying to analyze the space usage of the system drive with other tools can give you misleading information unless you know how to interpret it -- which isn't very straightforward.

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Thanks for sharing your ideas. I enabled Folder Options/Show hidden files, opened system drive in Explorer, select all, Properties ... (wait for some time) ... -> Size: 98.3GB, Size on disk: 99.2GB, which is close to the truth. The only thing it did not count was the hiberfil.sys (does not show up in the C: root), although the total is correct. Need more research, maybe DU by SysInternals will shed some light on it. –  Neolisk Oct 11 '11 at 17:52
    
".\du.exe -u c:", Size: 96.41GB (103,519,911,585 bytes), Size on disk: 96.40GB (103,509,556,654 bytes). Yes, size on disk is less than regular size. Windows 7 cannot agree with that. –  Neolisk Oct 11 '11 at 18:04
    
That Explorer got close by selecting all and viewing properties is a coincidence. It's not accurate, nor is it designed to be. du.exe is as accurate as can be, with the permissions your account has. –  afrazier Oct 11 '11 at 18:15
    
New version of TreeSize Free (v2.5): 103.42GB, previously used v2.4, the problem is with growing MS SQL server logs. Hard to believe, but now it started to show up (almost) right under Total Commander. FAR is showing 116.1GB of used space, although there is only 111GB available, but that's another story. @afrazier, I will mark your reply as an answer. Thank you. –  Neolisk Oct 11 '11 at 18:22
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Do the tools you used count the pagefile? I ran into a similar issue a while back where I was trying to account for 12GB of "unaccounted for" data and I had completely forgot about the pagefile.

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Pagefile is disabled. hiberfil.sys ~ 3GB on my system, and was included in those 75GB. –  Neolisk Oct 11 '11 at 17:41
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Did you look at your System Restore Points ? You can find a great post on it here

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Uh, from the question: "Shadow copy is using up to 5GB with the current usage of 1.36GB." –  Shinrai Oct 11 '11 at 15:53
    
I had the impression that the term "Shadow Copy" was only referring to the "Previous Versions" and not to global snapshots, I'll check again because it seems I was wrong. –  Shadok Oct 12 '11 at 12:44
    
Pre-Vista, System Restore was its own animal, but that's no longer the case. blog.szynalski.com/2009/11/23/volume-shadow-copy-system-restore –  Shinrai Oct 12 '11 at 14:18
    
I didn't use Vista at all and I only have little experience with 7 but I did use XP a lot so my knowledge is a bit rusty, thanks for the info ! –  Shadok Oct 12 '11 at 14:32
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