HDD free space error?

Hi. I have a 1TB external drive (USB) which Windows reports to have 145 GBs of available free space. Yet when I copy folders which amount to 80GBs to the drive, I get a report before completion that the drive is full and not all the folders making up the 80GBs will copy across.

The actual usable space on the 1TB is drive is shown in Windows (and Disk Management) as 931GBs: the folders already present on the drive total 827GBs. Well that doesn't make 145 GBs free, but nevertheless still leaves enough space in theory for me to copy my 80GBs there...

The Recycle Bin and System Volume Information folders on the drive show as empty, and System Restore is not set to touch the drive at all. 'CheckDisk' (or, 'Error Checking' in Properties/Tools) found no problems.

Can anyone help me resolve this please? It just doesn't 'add up'!

Thanks.

EDIT: Just realised that the disc is set as compressed. I guess that is probably the cause - though I still can't quite make sense of the numbers?

​Windows 10 '20H2' (Build 19042.928)

Hello @martinlest,

Just a thought, have you got ANY other Partitions or Hidden Partitions?

You could use this for just for the Disk / Drive you are referring to . . .

 Partitions Screenshots

Please post [ upload ] a screenshot of your partitions.

IMPORTANT:

• By default, some columns are compressed. FULLY widen ALL the columns, making sure that the contents within them are FULLY visible.

> How to Post a Screenshot of Disk Management at Ten Forums

About Mini Tool Partition Wizard:

Mini Tool provides users with portable partition software to better configure disk and partitions, bringing brand new user experience and overcoming the many shortcomings in Windows Disk Management.

Both 32-bit & 64-bit downloads available.

> Mini Tool Partition Wizard – FREE
> Mini Tool Partition Wizard [ Portable ] - FREE

UPLOAD SCREENSHOTS:

> How to Upload and Post Screenshots and Files at Ten Forums

I hope this helps!

I just realised that the disc is set as compressed. I guess that is probably the cause

You just answered your own question.
Also, if the drive is formatted FAT32 You cannot copy files that are larger then 4GB. You can only copy files larger then 4GB if the drive is formatted NTFS.

The drives are unpartitioned NTFS by the way

Each drive needs at least One Partition to Format it NTFS. Maybe you meant there is only 1 Partition and no extra partitions?
Why are you compressing your drives? Compression was used in the old days, because of the size limitations of HDD's and the cost of larger drives. Today, Drives keep increasing in size and coming down in price, there is no reason to compress a HDD these days. Just get a bigger drive if you run out of space.