Quoting from the release notes:
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Specific versions of graphical management interfaces are compatible with certain versions of Data ONTAP. For example, if you want to use OnCommand System Manager with Data ONTAP 8.2, you need to install OnCommand System Manager version 2.2. Earlier versions of OnCommand System Manager and other graphical management interfaces will not work with Data ONTAP 8.2. Visit the Software Download page to learn more about the supported versions and availability of graphical management tools, such as OnCommand System Manager, SnapDrive and SnapManager products, Virtual Storage Console, and more.
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When Snapdrive 6.5 or older tries to talk to the controller to determine license status, the communication fails because the license API doesn't support 8.2. For this reason Snap Manager products will NOT work. Wait until a newer version of Snapdrive is released that supports 8.2 to test 8.2
Also, OnCommand Core, VSC, Snapdrive, System Manager, and SnapManager must all be upgraded to versions that support 8.2 BEFORE attempting to upgrade to 8.2. Otherwise, you will have to do a downgrade (revert_to) of ONTAP which is disruptive.
FYI, SnapDrive 6.5 fully supports server 2012, together with iSCSI host utilities 6.0.2 for Windows. Make sure you're using that version.
I dont think the ONTAP version cares what guest OS version you are using provided the tools (such as SnapDrive) support it.
-Ed