One of the challenges seen in clustered Data ONTAP (cDOT) was the migration of block-based storage from ONTAP operating in 7-mode. Even with a supported tool set, the transitions were clunky, tedious and had to be done offline.
Starting in cDOT 8.3.1, support for foreign LUN import from 7-mode systems was added to make that transition easier, as well as minimizing (or eliminating) downtime for LUN transitions.
With this new feature addition, there is also an excellent how-to TR on the process available as of July 2015. Be sure to check it out here: