Hi,
I saved all my projects on an external drive.
I formatted  my audio drive and few days after I notice that a lot of memory had already gone...It's a 900 gig space and after I opened 3 or 4 projects containing 3 gigs, I saw that there was only 600 gig left...and it's not the 1st time it happened...any idea of what could I'm doing wrong.  I know there is a place where we can clean the audio disk inside Sonar and I never use that...could it be something there?
Ty

Start by using WinDirStat to find out what is actually taking up the space.

Thanks slatabartfast, I'll take a look for sure!
 

I did that but, my disc is only audio.  So the program Windirstat just show me big blue balloons and when I clic on one, it tell what is there.  I miss something.  The disc is 930 gig andI take maybe and 100 gig of space but there are only 279 gig left...
maybe, I will try a format again...