We're sure this is not NAS. Plain fibre cards with SCSI devices being detected. We probe down the fibre cards which generates
/dev/sdn devices. We then blend the four paths to form multipath devices that we then use as a PV to add to the volume groups.
Much of this is automatic first time, but we did a bit of the hokey-cokey on our first few attempts so after clearing old definitions away the auto-discovery stopped.
Everything seemed fine whilst we had the new LUNs in the VG and in use but the old ones not removed. A boot would complete normally, it's just when we've removed the old LUNs from the VGs that it went off. Perhaps the old LUNs (as part of the VGs) had the VG information on them and so they would respond and the VG would vary on even though there were LUNs still initialising.
All very confusing though
Robin