I have an 8 blade Windows Hyper-V 3 cluster. Each of these blades has access to a 5.00Tb LUN (Cluster Shared Volume), created through Snapdrive, stored in a 5Tb volume, where each of my 80-odd virtual machines' vhdxs are stored:
Storage efficiency is enabled, and after the last run, these are the results:
However, Windows still reports only 439Gb of free space:
I don't have any snapshots or QoS setup on this volume.
The vol reports that it has 2.42Tb free space (due to dedupe I assume)
The lun reports that it has 1.11Tb of free space
Windows only reports that there is 418Gb of free space...
Where did the other 718Gb go that's supposed to be left in the LUN?
How much can I safely decrease the size of the volume now that it is deduped?
Yes, he is correct. If order to "see" the real available space, you would need to use CIFS shares over SMB 3.0 for your Hyper-V storage. This way, NetApp's WAFL is handling the underlying filesystem instead of Windows and it has visibility into the actual free space. It has other added benefits as well, take a look at http://www.netapp.com/us/media/tr-4172.pdf for more details.
Again this is correct, you do need to be running clustered OnTap for this, feature not available in 7-mode. You'll want to check which versions of cdot 8.2 onwards i think, check the interoperability matrix to be sure.