So far plagued with boot from SAN issues. Through MDS fabric at that!
Found it to be an issue with the 1340 VIC cards. Booting via Boot Policy through the 1340 card causing intermittent Boot from SAN errors. Boot through 1380 and disable 1340 ports for work around.
B420 Server running 3.1(1H) code with 1340 (1), 1380 (3), and Port Expander on 1340 (2).
If anyone has a diagram of how data flows through a B420 with 1340 (and expander card) and 1380 with a 2304 IOM upstream please send. Will add to this article and as a post. So far have not been able to find that diagram from Cisco. That don’t mean it don’t exist though, someplace.