17:22:00 <nikolam> I have seen boot USB flash not showing as the device before and therefore not mountable, 
17:22:01 <nikolam> I connected it with putting USB 3.0 flash drive into 2.0 USB port. When I have put it in 3.0 port it shows itself in ' diskinfo ' and can be mounted and updated. 
17:23:44 <bahamat> Yeah, that's an issue with the xchi driver not recognizing some devices. Best thing to do is contact illumos-discuss.