[eugeneg]

I have a secondary internal disk that is shown in Windows Explorer on my Vista PC as having 698GB with 145GB free. Hence, you may assume, 553GB in use. But if I right click in Windows explorer after selecting all files in the root directory, I am told only 192GB are in use. Where are the misssing 361GB ?

I have hidden files displayed. WinDirStat shows 360GB as <unknown>.
I have run CHKDSK and no problems were found. The disk is NTFS formatted in a single partition with no compression. Norton software nas never been installed on this PC.

[Mumbodog]

Maybe shadow copies (system restore points)

Use an Ubuntu boot CD, see if you can see the unknown files.


.

[aka Brett]

There is a norton product out,that can cause this problem...dont remember the name of it but it takes the place of system restore and also lets you recover deleted data

[dominicd]

This seems like a simple obvious question but have you run diskclean up... Vista loves to dump states to disk if put into sleep and hibernation...

[TheOutcaste]

Why there is a difference in the space free/space used shown by Drive Properties, and selecting all the Files/Folders on a Drive.

The space shown as used by a drive by right clicking the drive and clicking Properties will always show more space used than highlighting all folders does (unless there is a problem with the drive of course).

When selecting all the files then doing a right click - Properties, you will only be shown the total for the files and folders your account has permission to view. Files and folders you don't have permission for won't be included, like the System Volume Information folder where Restore points are stored.
You also won't see space used by the NTFS MetaData files, or by any files that have Alternate Data Streams (ADS), or, on Vista/Win7, space used for Shadow Storage, aka Previous Versions. Vista/Win7 Basic and Home still create previous versions, even if you don't have access to them as in the Ultimate/Business versions.

System Restore/Shadow Copies can use up to 12% of the partition on XP, and 15% (or more, 15 is the default) on Vista/Win7. On a 1 TB (931 GiB) drive that's 111-140 GiB

When viewing the Drive properties, it shows the space free/used based on the Volume Bitmap file $BITMAP, which shows everything, as permissions or hidden files aren't involved. So there will always be a discrepancy.

You can use one of these apps to see where space is being used. Folders you don't have access to will show a size of Zero. Some of the apps will flag them with an Access Denied message (TreeSizeFree does, WinDirStat doesn't).

Hard Drive space usage
WinDIRStat
TreeSize Free
Disk Detective
JDiskReport

To see the amount of space used by System Restore and Shadow Copies on Vista/Win7:
Open an Administrative Command Prompt:
Click Start, type cmd, press CTRL+SHIFT+Enter (hold CTRL+SHIFT until the UAC prompt appears)
Type vssadmin List ShadowStorage and press Enter

If you want to change the size allowed to be used, enter this to see the format to use:
vssadmin resize shadowstorage /?

XP can also use Shadow Storage, though that's not as common.
Open a Command Prompt:
Click Start, type cmd, press Enter
Type vssadmin list shadows and press Enter

You can use chkdsk to see how much space some of the NTFS MetaData files are using. And to see if you have space allocated that shouldn't be.
Open a Command Prompt (Elevated Prompt on Vista), then type chkdsk C:. It will run in read only mode, then give a summary like this one:

 78148160 KB total disk space.
 44055172 KB in 145290 files.
    38636 KB in 9639 indexes.         <-----
        0 KB in bad sectors           <-----
   342908 KB in use by the system.    <-----
    65536 KB occupied by the log file.<-----
 33711444 KB available on disk.

Note that if you do have drive errors, chkdsk may exit without completing the check, and won't display a summary. In that case, or if it indicates other errors, run it with the /F switch (chkdsk /F C:), says yes to schedule the check at the next boot if needed, then reboot.
Total the indicated lines. In this example, 38,636+0+342,908+65,536=447,080 KiB=436.6 MiB=0.426 GiB, so nearly 1/2 GB of space that won't show when totaling the files. On some systems this could be 1-2 GiB or more.
The $BadClus file will use a little bit of space (1-2 KiB), even if there are no bad sectors.

On this system I have 4,188,078 bytes used by ADS. It's only 4 MiB, but you may have more.

The following batch file will total up the space used in ADS on your system. You'll need to download Streams from the SysInternals website, then edit the batch file to point to the folder you put the streams.exe file into. You may also need to edit the Set _Tab= line so there is a single TAB after the equals sign, as TABs often copy as several spaces instead of an actual TAB character.
It will check the C: drive. To check a different drive, edit the Set _Search= line:

@Echo Off
SetLocal EnableDelayedExpansion
:: Note, the following line consists of a single tab after the = sign. If you copy this off the web, you may need to edit this line.
Set _Tab=    
:: Edit the next line to point to the folder you copy the streams.exe file to.
:: You can download Streams from http://technet.microsoft.com/en-us/sysinternals/bb897440.aspx
Set _Stream=C:\Scripts\streams.exe
Set _Search=C:\
Set _Total=
For /F "tokens=4 skip=4 Delims=:%_Tab%" %%I In ('%_Stream% -s %_Search%') Do Set /A _Total=_Total+%%I
Echo Total Space used by Alternate Data Streams is %_Total% Bytes

Delete System Restore points:
Start | Accessories | System Tools | Disk Cleanup
For Vista/Win 7 only:

• Click on Files from all users on this computer
  You'll get a UAC prompt if UAC is enabled.

Select the drive and click OK
It will check the disk, then bring up the Cleanup dialog.
Click the More Options tab
The bottom section allows you to delete all but the last System Restore point.

RollBackRx and possibly Norton GoBack, as well as other programs of this type, can also use a lot of disk space that is invisible in Windows Explorer.

[dominicd]

Very nice tutorial...

[eugeneg]

Many thanks for the replies.
I think the space must be taken up by backups taken with the Vista bundled backup application. These all show as 0 bytes (yes, I have tried recovering a file). Unfortunately I have no access to these folders unless I explicitly grant myself access - a very time consuming job for several hundred folders. I wonder if there is a way of granting myself (in the Administrators group) read access to all in one go rather than individually setting eache folder.

[eugeneg]

http://support.microsoft.com/default...&Product=winxp

[TheOutcaste]

You can propagate permissions to all the subfolders and files in a tree from the parent folder.

On the Security tab for the Parent folder, click Advanced
On the Permissions tab, click Edit
Add or Edit the Permissions as needed, and check the box for Replace all existing inheritable permissions on all descendants with inheritable permissions from this object

That should change them all at once.

May have to take ownership of them all first though.