Where’s my disk space?

Where’s my disk space?

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I have worked a few customer cases lately that have had the same issue.  Explorer shows that a disk has plenty of disk space available.  When you look at the same disk in Disk Management, you see that it is almost full.

 

One thing that can cause this is leftover shadow copies.  Some backup software will create a persistent shadow copy and after they have backed up the shadow copy to the designation, they fail to delete the original copy that is stored on the volume.

 

Here’s an example:

 

Drive F: on your server is backed up weekly.  This drive stores files for users on your network.  When checking in Explorer, you notice that it says you have 250GB of free space left.  You look in Disk Management and you notice that the F: drive only shows to have 10GB of free space left.  Some of my customers have noticed the difference in disk space after running a chkdsk also.

 

The first thing that I have had my customers do is go to the properties of the drive in Explorer and then click on the Shadow Copies tab.  When you look here, you can see that there is space being used for Shadow Copies on the drive.

 

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A word of caution:  Avoid deleting snapshots if you don’t need to.  They may have been setup so that users could revert to Previous Copies of their files. 

If you do not need these shadow copies, then there are two ways that you can delete them.

 

1.   Use the VSSAdmin Delete Shadows command.

Example:

Vssadmin delete shadows /For=F:

 

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2.    In some cases, the shadow copies could not be deleted this way.  In order to remove the shadow copies, we had to set the maximum storage down to 300MB and Windows deleted the entries automatically.

 

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Once you set the maximum to 300MB and click on OK, any shadow copies that are over 300MB will be removed from the drive and your drive space should be reclaimed.

 

“But Wait AskCore, I am missing space on a drive that has no data on it and on the Shadow Copies tab, it shows that there’s not any space used for shadow copies.”

 

This too could be shadow copies also.  There is a term called “Shadow Storage” that is used to describe where the shadow copies of a drive will be stored.  You can choose the have the shadow copies for a drive to be stored on another drive.

 

Here’s an example:

 

I have an E: drive with data on it, but don’t want to use my free space to store shadow copies of the drive, so I am going to place the shadow copies on my F: drive.  In order to set this up, go to the properties of the E: drive and then click on the Shadow Copies tab.  Select the E: drive and then click on Settings.  The following dialog box will pop-up.

 

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Under the “Located on this volume:” option, you can click the drop-down and select another drive to store the shadow copies on.  In this case, I have chosen my F: drive.

 

After changing these settings, any snapshot of the E: drive that I create will be stored on the F: drive.  My F: drive on this machine has nothing on it, but after taking some snapshots, Explorer will show that space has been used even though I can’t see any files.

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When looking on the Shadow Copies tab, the F: drive doesn’t show to use any space for shadow copies.  If you notice beside the E: drive, it states that it is using 300MB on the F: drive.  By default, this column is too narrow to see past 300MB, so you may not realize that the F: drive is being used for storage.

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Well, there you have it.  I hope that this helps you out.


James Burrage

Senior Support Escalation Engineer

Microsoft Enterprise Platforms Support.

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  • Why was the design decision made to exclude shadow copies from Explorer's free disk space value? Do any other Windows components do the same thing?

    Besides diskmgmt.msc, how else can you get a "true" free space value - command-line, WMI, Vbscript, PowerShell?

  • Explorer only shows you the what you have permissions to see, not what the system has permissions to.  Running chkdsk without any switches should also show you the true disk space usage.

  • Given the examples in this post and the fact that Explorer incorrectly counts hardlinked files as used space when making its calculations of freespace, there is a case for removing Explorer's ability to display free space entirely. Why is better that Explorer displays misleading numbers that nothing at all?

    Instead, would it be preferable for Explorer to launch a secondary application - with execution level 'requireAdministrator' - that does understand shadow copies and hardlinks and can correctly display freespace?

    Explorer is really is a FAT/FAT32 oriented app still being used today in the NTFS era for historical and familiarity reasons. Time for a new shell?

  • NOTE: The best way to know your real free space is to look at the properties of the drive.  Trust the pie chart.  The reason is that it doesn't rely on adding misleading file sizes together.  This method instead queries the file $BITMAP to determine the amount of in use clusters.

  • Hi all, for those people wondering about current free disk space, ntdebugging blog had 2 nice articles regarding NTFS and reported free space, you may find it helpful:

    blogs.msdn.com/.../ntfs-misreports-free-space.aspx

    blogs.msdn.com/.../ntfs-misreporting-free-space-part-2.aspx

  • Drewfus, have you tried using FolderSizes (www.keymetricsoft.com) for this task? It does a much better job at analyzing file systems and producing useful disk space allocation reports.

  • @Larry Moran: I'll have a look at that prog, thanks. I posted my command wish list to the Win8 Dev Preview forum. social.msdn.microsoft.com/.../5891df3c-5060-4cb6-8c80-c4dd11c9df35 Drive space tool is #35.