Something to keep in mind. 2TB is the maximum size for an MBR partition, so you can't just grow it when you run out of space. Even more dangerous than that in this particular case is that LUNs go offline when 100% full. So... your 2TB MBR partition fills to 100% and goes offline -- and you can't extend it to bring it back online. That's all she wrote. Roll back to a snapshot where the LUN wasn't full and hope that the data lost in the process wasn't important.
If for some reason this data has to remain on one LUN it's time to start migrating data. Present a new LUN and partition as GPT to go above the limitations you're currently facing.
Resizing a cluster volume is the same painless operation of extending a single host LUN. No downtime or IO interruption, just extend from the active node.