How to clear 217Gb of space on my C drive?

Question

I have a Dell XPS 15 (2013 model L521X - Windows 7) with a capacity of 680.3 GB on the C drive.

But WinDirSat says that 217.4 GB of that space is <Unknown> and I can't access it!  SpaceSniffer says that 215.8 GB is 'unaccessible space'!

The 'unknown' space is getting bigger by at least 1 GB a week – given the rate of increase, I think that this problem has existed since I got the laptop in 2013 or soon after. My laptop is now out of warranty and the explanation from Dell was laughable – they said that this amount of unusable space was normal!!

Has anyone experienced this – or know of any solution other than the ones I have already tried?

The 217 GB of Unknown space is definitely not system restore points. I have never set any restore points and have gone through the process to delete all restore points.

WinDirSat and SpaceSniffer don't list any files that are in this space – so there are no files I can delete. I have used CCleaner and the Windows Disk Cleanup to delete unnecessary system files.

I noticed that when clicking on the 'Cleanup System Files' button (in the Disk Cleanup), the progress dialog gets stuck on 'System error memory dump files' and then gives up. Perhaps there is some sort of logging or memory dump that is stored in an inaccessible directory

I don't have any other problems with the HD, RAM or Windows. Although I did have some problems when I first got the laptop with the Webcam not being correctly connected to the USB and got a couple of blue screens.

Answer 1

Most disk space management tools do not list alternate data streams, do not properly calculate hard-linked files and do not list the space in folders that you do not have access to, e.g. the folder "System volume information" folder in the drive's root. Without a tool that does all this correctly, you won't be able to get correct results for directory sizes. TreeSize Professional does this job once you activated the option "Track NTFS alternate data stream and hardlinks" in its options and have started it as administrator. Full disclosure: I am one of the developers of the TreeSize product family. A free 30 day trial is available.

In rare cases the structure on the volume may be damaged. in this case CHKDSK /F /SCAN /SPOTFIX might help.

In case the "System Volume Information" folder seem to be unreasonably large, you may reduce the space that Windows may use for shadow copies using this command: vssadmin resize shadowstorage /For=C: /On=C: /MaxSize=1GB. In this example, the space is set to 1 GB. As a quick solution you may execute this command: vssadmin Delete Shadows /For=C: /Oldest. It will delete the oldest shadow copies.

For both commands you need to run CMD.EXE as administrator.

Answer 2

I had the same problem and read millions of pages explaning delete this that and those but none of them help me to find UNKNOWN files eating space in my disk.

In my case I found the solution by chance and it was easy, I hope ti may work for you.

1. Right click on C drive (you may use the disk you need) and open properties
2. There should be 2 options at the below ;first one is telling to compress disk and the second one is telling indexing filed and even contents of files please be sure you unchecked this option.
3. Restart your computer.

As I said in my case this solved my problem but also be sure that you uninstalled programs like Dell Backup Recovery Tool too.

Let me explain why unchecking indexing solved my problem.I know indexing is a good thing but if you have 40gb Outlook PST file indexing is not helping you but just eating your free space.

I hope I could help you.

Answer 3

I'm currently running SpaceSniffer 1.3.0.2 on my Windows 10 and noticed the appearance of 4.4 GB of "Unaccessible space".

Running another instance as administrator revealed that that space is actually being used:

• 2.0 GB in pagefile.sys, probably non-userspace swap.
• 1.3 GB in "C:\Program Files\WindowsApps".
• 1.2 GB in "C:\Windows", mostly "System32\config", "ServiceProfiles", "InfusedApps", and "System32\winevt" folders.

Also listed are:

• 6.8 GB in "C:\System Volume Information".
• 578.3 MB in "C:\ProgramData\Microsoft\Microsoft Antimalware".
• 170.0 MB in "C:\ProgramData\Microsoft\Windows Defender\Scans".

The data in System Volume Information appears to be restore points and locked file buffers made by Volsnap; it's currently 0 bytes, which matches error 25 in the system log.

Answer 4

The first thing to check in this situation is just to make sure you're running your space usage scanner with admin privileges (right-click, Run as administrator).

Otherwise there's a good chance there will be system files that you can't access, and this unaccounted space will show up as Unknown.

Answer 5

Have you looked at your indexing, Windows.edb, file? A co-worker of mine had an issue similar to this where a large amount of disk space was being taken up why the Windows indexing service. We only found out about the issue after the user complained about running out of disk space.

Followed these instructions and deleted the file.

Answer 6

In case of "System Volume Information" you can use the following to cleanup.

1. Open an elevated command prompt.
2. In the elevated command prompt, type wmic and press Enter. After a few seconds wmic:root\cli> will appear.
3. Type the command shadowcopy delete and press enter.
4. You will now be asked Y/N for if you wanted to delete the available shadow copies one by one. Type your answer and press Enter after each one.

After this process you can type vssadmin list shadowstorage in order to see the allocated space and also that the storage was erased.

Answer 7

this is a 2022 update,

• SpaceSniffer 1.3.0.2 is on Win10 unable to read 300+GB of "Unaccessible space". OneDrive contents reported in only few GB range.
• WinDirStat 1.1.2.80 is able to discover the above space as files in my personal and work OneDrive, over 200+GB as of now and still scanning after 4minutes.
• WizTree 4.10 does an initial scan just under 7secs reporting 271+GB used by OneDrive.

I guess the newer tools and versions are reporting much more accurately and quickly.

Answer 8

2024 Update for space sniffer: For me it suddenly started showing unaccessible space, so I checked storage usage in Windows settings, from where I found that size of this unaccessible chunk was same as a OneDrive account. On space sniffer I made a new scan, giving it path for the OneDrive folder, and it scanned it just fine.

So at least for space sniffer, the answer is to do another scan directly on OneDrive.

Answer 9

From a command prompt, run chkdsk /f repeatedly until there are no errors (you may need to reboot if it's a system drive).

As recommended in the comments, check for restore point usage.

Next, many applications don't see space used in hidden and/or system folders, and many programs (antivirus, for example) store stuff in those folders, so you may need to run dir /ash to get a list of system and hidden folders followed by dir <foldername> /ash /s to find out how much space the folder using (you may need to drill down into it to find the offending files).

Answer 10

In my case the problem was offline files. I work for a large corporation and we had several multiuser windows 7 clients. The problem was the synchronization of "MyDocuments". When 10 users synchronized these folders we ended up with 50+ Gb in C:\windows\CSC and his space does not show easily. You have to take ownership of many folders but if you do the numbers make sense. I am trying to reinitialize the cache but it seems we have GPOs which determine this behaviour. Again makes sense for single user clients but not for multi user.

So , look for hidden system files. Would be nice if there was a tool, which could show them.