Missing disc space

Hi. I 'permanently' deleted (i.e. not to the Recycle Bin, which is empty) about 600GBs worth of files from a 5TB external (USB3) HDD I use for backup, in order to copy new files there. But according to Explorer I have gained only around 200GBs of extra space on the drive by doing so. I obviously expected about 600GBs of space to be freed up! Disk Management shows the same thing, only just over 200GBs free. How is that possible when I know I deleted almost three times that amount? I cannot now copy the new files to the drive, as they need about 550GBs of space.

Googled this, and looked around the forum here, but to no avail. Has anyone any idea why this has happened, and if it's possible to free up that space now? I ran Error Checking (chkdsk) from the properties window, but no errors were reported.

O/S = Win10 Pro (Build 18363.1082)

Many thanks!

Could any of the files have been hard links? Only likely if system files, but you never know. There are various ways to check existing files (you can't really check the deleted ones!), I happen to have just re-installed Link Shell Extension, found here:
Link Shell Extension
so I know it works under W10. I have used it on & off since XP days to quickly show in Explorer which files are links.

Hi. Thank you for the reply. For one reason or another, I use Link Shell Extension on an almost daily basis. Very few if any in this case were hard links..

Could they have been compressed?

Could they have been compressed?

Yes, the whole disc is compressed. That would explain it, wouldn't it (though it's a huge difference. 600GB deleted, c.200GB recovered: the same files (the originals) compress to about 50%)? The 'penny dropped' the moment I read your comment I'll test the compression out a bit more tomorrow and then mark this as 'solved'.

(I'm clearing some space on the drive anyway, by moving files to a second one. With about 1TB worth of files in total, it'll be an all-night job, I think (and of course both Windows 10 and Windows 7 copy speeds start very fast, but soon slow down)).

Thank you

You're welcome - unusual for me to get in first with any sort of answer. The level of compression you can get depends on how 'compressed' the file is in its 'uncompressed' state (tortuous language there): jpgs being squashed up already, or mp3 files, hardly compress at all. Plain text files and logs are best.