Wipe Free Space Vs. fsutil

CCleaner for Windows
1

Hi, I just learned about fsutil file createnew C:\Blank.File 10000000.

I created a 50gb file in 1 second I went to properties and it said its 50gb size on disk.

CCleaner takes a good hour and a half for 70gb fsutil takes 1 second..

I was wondering the difference between the two other then CCleaner being exact and fsutil having to manually enter size.

Please tell me the difference between the two.

2

Probably the difference between allocating and overwriting. For a start, CC will write 70 gb of zeroes on your disk, which is no mean task. And Fsutil? As far as I can see it will create a few entries in the various file and space management tables, and write no data at all.