OK, so MPxIO “Just Works”. I exposed a small number of LUNs (four, to be precise) from each of a pair of SataBeasts. One of those had something on it: to wit, a prototypical “bb-archive” zpool.
zpool status etc. will show the MPxIO devices that comprise the particular zpool in question – but what about the other seven LUNs? And what about when it comes to stiching LUNs together, and so on? This is going to turn into a cross-referencing nightmare!