Thanks for your reply.
Because that CIFS volume is accessed by our customer and he's only authorized to have 20TB in logical space used. However, he's using more than that with deduplication.
We applied the "is-space-logical-reporting" option to the volume so that from the client view (windows OS), he can check how much logical space is used.
Now, we want to be sure that 20 TB in logical space used won't be exceed. But don't really know the type of quotas that is needed on that situation. The volume and the CIFS share is dedicated to the customer without any qtrees.
We just want to limit the logical space used directly on the volume.
CDOT version : 9.7P8