Than depending on your quota policy a treequota or client du can count more or less than the actual space used on the disk  I suggest to see the deduplication and quota manuals for details on how it works with single-instanced and compressed files
We have a filesystem, which has 7 tree quotas and they're shared out via CIFS. My understanding was that data, not quota size, factored into overall filesystem usage. But that seems to not be the case with this one.  Here's the FS usage:   I added up the quota usage, and it comes in at 1983GB. I also checked the savvol, which is at 1.5TB. I'd expect to see the usage of this volume at just under 3.5TB.  The space given to tree quotas is 5900GB.  Can someone help me understand why the volume is showing 6.8TB used?  Thanks, Joe
Need help understanding filesystem usage