Wiping free-disk space?

[AstroBenny]

Can someone explain when these points apply? Examples maybe? Thanks

 

Wipe Free Disk Space limitations

CCleaner can't wipe every deleted file from your free disk space. There are some limitations, because of the way Windows stores some files.  Here are some examples:

• The file has been overwritten by another file (so no need to overwrite this again)
• The file had been overwritten by another file before you ran CCleaner, but the second file has now been deleted as well.
• The file was created almost exactly when you ran CCleaner.

[Electronics Wizardy]

There is no reason to do this. If you want your data to be secure, encrypt your hdd. It won't speed it up.

 

These are due to how ntfs works.

[AstroBenny]

2 hours ago, wrathoftheturkey said:

First: files aren't really erased, they're more like whited-out -- they're wiped when you write a blank to their sectors. So if a file's overwritten (whited out, basically, replaced with something else) there's no need to erase it, because it's already gone. When you hit delete, Windows hides the file, until it's ready to be overwritten by the next thing(say a cat video). Since that cat video's taken up the space where the old file was, there's no need for CCleaner to write and delete random data to that sector dozens of times. 

Second: Someone deleted the cat video in Windows.

Third: no idea, but you can fix that by running the program again, I suppose.

Thank you!