[SOLVED] Windows says I have 3,35 TB of data on my 2,72 TB hard drive; can't backup

[julianomnunes]

I have two 3 TB hard drives and I used to back one up to the other, so I would always have a duplicate of my files. I've been doing this for about a year now.

I hadn't updated my backup in a while - a month or so, and when I tried to do so tonight, the software I use (FreeFileSync) told me the backup couldn't be done because there were 3,35 TB of data on the source drive, and it wouldn't fit on the target drive. Again, both are 3 TB drives - it shows as 2,72 TB on Windows because bits, bytes, all that stuff.

So, thinking it might be something with FreeFileSync, I go into Windows Explorer to check the properties of the drives. It shows the source drive with 2,72 TB capacity, 2,05 GB used space and 692 GB free space.

I then format the target drive, and it shows as having 2,72 TB capacity and 2,72 TB free space.

Then, I try a simple copy all / paste all operation in Windows Explorer itself. It begins doing the pre-copy calculations... and then tells me I need an additional 635 GB to perform the copy - which is roughly the amount it would take to reach 3,35 TB.

I have been messing with computers for about 30 years and have never seen anything like this. How is this possible? Could I be doing something wrong, a rookie mistake, maybe?

Both drives are in good health. The source one is new, I got just a few months ago. The target one is a little older, 5 or 6 years maybe. But I've always kept it in good care, running periodical diagnostics to check if there was any trouble with it. There never was; it would always check out fine.

Last week I removed a faulty, older 240 GB SSD from my PC. It wasn't being used, it just sat there being recognized by the BIOS but not by Windows, so after fighting some laziness I finally got around to getting it out.

Other than that, there were no major changes to the computer. Nothing installed or removed other than the weekly or monthly CCleaner check. Maybe some updates to some games also, but they're all installed on an SSD.

Appreciate the help!

My specs:
Intel Core i7-4790 3,60 GHz (overclocked in BIOS to 4 GHz)
Gryphon Z97 motherboard
16 GB DDR3 RAM
Stock cooler
NVIDIA GeForce 970X 970
600W power supply
480 GB SSD
2x3 TB HDD
Windows 10 Pro 64-bit

 

[USAFRet]

Is the source drive possibly compressed?

Is there maybe some hidden data (600+GB) residing on the target drive?

 

[julianomnunes]

Is the source drive possibly compressed?

Is there maybe some hidden data (600+GB) residing on the target drive?

No, there's no compression. I thought of that and checked.

As for hidden data, I don't think so. I've never set any files to hidden. But even if there were hidden files, wouldn't they show up as used space anyway in the properties of the drive?

I just tried something else: I selected all the folders in the drive and clicked properties. I says it amounts to 2,99 TB - which is a different number, but still more than the drive can hold.

 

[USAFRet]

Recycle bin maybe?
Leftovers from previous FreeFileSync actions?

 

[julianomnunes]

Recycle bin maybe?
Leftovers from previous FreeFileSync actions?

Recycle bin is empty.

I wouldn't know about leftovers... I always used FreeFileSync to update the backup; copy files from the source to the target and that was it. Could that have somehow created files on the source drive, and maybe hidden them?

 

[USAFRet]

Recycle bin maybe?
Leftovers from previous FreeFileSync actions?

Recycle bin is empty.

I wouldn't know about leftovers... I always used FreeFileSync to update the backup; copy files from the source to the target and that was it. Could that have somehow created files on the source drive, and maybe hidden them?

Possibly.
I used to use FFS, but gave it up in favor of better options.

Since this is a "backup" drive, consider formatting the target drive and starting over.

 

[julianomnunes]

Recycle bin maybe?
Leftovers from previous FreeFileSync actions?

Recycle bin is empty.

I wouldn't know about leftovers... I always used FreeFileSync to update the backup; copy files from the source to the target and that was it. Could that have somehow created files on the source drive, and maybe hidden them?

Possibly.
I used to use FFS, but gave it up in favor of better options.

Since this is a "backup" drive, consider formatting the target drive and starting over.

What backup software do you use? I only used FFS because I couldn't find anything better. I'd love to hear suggestions!

I actually formatted the target drive before writing the post, thinking it may somehow fix the issue, to no avail. The source drive keeps showing having more data than its capacity.

I'm stumped here. I've tried googling every way I know how, but it seems my problem is not at all common.

 

[USAFRet]

What backup software do you use? I only used FFS because I couldn't find anything better. I'd love to hear suggestions!

I actually formatted the target drive before writing the post, thinking it may somehow fix the issue, to no avail. The source drive keeps showing having more data than its capacity.

I'm stumped here. I've tried googling every way I know how, but it seems my problem is not at all common.

I use Macrium Reflect. Works very well. Far more fine grained than a simple file/folder copy tool like FFS.
Read here, and scale up or down as your needs dictate:
http://www.tomshardware.com/forum/id-3383768/backup-situation-home.html

 

[julianomnunes]

What backup software do you use? I only used FFS because I couldn't find anything better. I'd love to hear suggestions!

I actually formatted the target drive before writing the post, thinking it may somehow fix the issue, to no avail. The source drive keeps showing having more data than its capacity.

I'm stumped here. I've tried googling every way I know how, but it seems my problem is not at all common.

I use Macrium Reflect. Works very well. Far more fine grained than a simple file/folder copy tool like FFS.
Read here, and scale up or down as your needs dictate:
http://www.tomshardware.com/forum/id-3383768/backup-situation-home.html

I'll definitively give it a try!

And I'll keep looking for an answer to my problem. Thanks!

 

[Solandri]

Do you know if there are any hard links? I believe the file size of a hard link is counted again in the total file size summary. So if you created hard links to a bunch of movie files, the disk would count the space the movies take twice, even though there's actually only one file (the second "copy" just points to the original file).

The other thing that's puzzled me is how Windows calculates file sizes for the WinSxS folder. That folder contains copies of older versions of dynamically linked libraries in case a Windows program was compiled with the older version and not the newer version. Microsoft people keep saying the size of that folder that File Explorer reports isn't its actual size, but I've never seen a clear explanation for what exactly is going on.

Finally, it is possible for a filesystem to become munged so some of the file info data is inconsistent. You can try right-clicking each folder and selecting properties to see its total file size, and compare against the size of the same folder on the backup. Oh wait you said you wiped the backup drive. Hmm... Ok, instead of trying to copy the entire drive at once, try copying one folder (and its subfolders) at a time. That way if there's an error in the file info which makes Windows think a file is bigger than it really is, the copied file should show the correct size on the backup drive. And when you right-click->properties each folder on the backup drive, you should see a file size difference from the original drive.

 

[julianomnunes]

Do you know if there are any hard links? I believe the file size of a hard link is counted again in the total file size summary. So if you created hard links to a bunch of movie files, the disk would count the space the movies take twice, even though there's actually only one file (the second "copy" just points to the original file).

The other thing that's puzzled me is how Windows calculates file sizes for the WinSxS folder. That folder contains copies of older versions of dynamically linked libraries in case a Windows program was compiled with the older version and not the newer version. Microsoft people keep saying the size of that folder that File Explorer reports isn't its actual size, but I've never seen a clear explanation for what exactly is going on.

Finally, it is possible for a filesystem to become munged so some of the file info data is inconsistent. You can try right-clicking each folder and selecting properties to see its total file size, and compare against the size of the same folder on the backup. Oh wait you said you wiped the backup drive. Hmm... Ok, instead of trying to copy the entire drive at once, try copying one folder (and its subfolders) at a time. That way if there's an error in the file info which makes Windows think a file is bigger than it really is, the copied file should show the correct size on the backup drive. And when you right-click->properties each folder on the backup drive, you should see a file size difference from the original drive.

I don't know anything about hard links, actually. How would I find if I have hard links?

The backup drive only contains personal stuff; the OS and all software are installed on a separate SSD.

I'm gonna try to copy one folder at a time and see what happens.

And I fell pretty silly now. I actually wrote on the original post that there were no major changes to the computer, but I completely forgot that I updated Windows a few weeks ago to version 1809.

Given that this version had its share of problems - deleting user files and all that, could it be it screwed up my hard drive's filesystem? I waited until it was stable and researched online to check if it was really safe before updating, but I think it might be a possibility.

Dang, I feel REALLY silly about forgetting to mention that.

 

[USAFRet]

I don't know anything about hard links, actually. How would I find if I have hard links?

The backup drive only contains personal stuff; the OS and all software are installed on a separate SSD.

I'm gonna try to copy one folder at a time and see what happens.

And I fell pretty silly now. I actually wrote on the original post that there were no major changes to the computer, but I completely forgot that I updated Windows a few weeks ago to version 1809.

Given that this version had its share of problems - deleting user files and all that, could it be it screwed up my hard drive's filesystem? I waited until it was stable and researched online to check if it was really safe before updating, but I think it might be a possibility.

Dang, I feel REALLY silly about forgetting to mention that.

An issue arising from the v1809 update is possible, but I think unlikely.
Yes, try copying it folder by folder.

 

[julianomnunes]

I don't know anything about hard links, actually. How would I find if I have hard links?

The backup drive only contains personal stuff; the OS and all software are installed on a separate SSD.

I'm gonna try to copy one folder at a time and see what happens.

And I fell pretty silly now. I actually wrote on the original post that there were no major changes to the computer, but I completely forgot that I updated Windows a few weeks ago to version 1809.

Given that this version had its share of problems - deleting user files and all that, could it be it screwed up my hard drive's filesystem? I waited until it was stable and researched online to check if it was really safe before updating, but I think it might be a possibility.

Dang, I feel REALLY silly about forgetting to mention that.

An issue arising from the v1809 update is possible, but I think unlikely.
Yes, try copying it folder by folder.

Update:

Well, I didn't figure out exactly what was causing the discrepancy in size, but I did manage to back up my files. I did some housekeeping, looked around and deleted stuff I didn't really need, reducing used space in the drive - as shown in Windows Explorer - from 2,05 TB to 1,90 TB.

Then I tried copying folder by folder and it all went all right.

Now both hard drives show the same amount of used and free space.

As the files I deleted had nothing in particular in common - different folders, file types, sizes, creation and modification dates - there's no way to know which one, or ones, were causing me trouble.

As I've been [strike]hoarding[/strike] keeping data on my source drive for some 10+ years, there could be any number of reasons for the glitch.

I guess the lesson here is: always back up AND do some housekeeping once in a while.

Thanks a lot to everyone who took the time to reply and make suggestions!