GRUB only sees first of 2 identically-configured drives in RAID 5 array?

Question

Has anyone ever come across a case where of the two (virtual) disks that are members of the same hardware RAID 5 array (LSI 9750), GRUB can only see the first?

It's a 100% hardware RAID 5, to the operating system both /dev/sda and/dev/sdb appear just fine and identically, however in GRUB only (hd0,...) is available, with no (hd1,...) to speak of?

I would understand if GRUB cannot (at all) see the members of the RAID 5 array, but why would it only see the first disk and not the second?

Answer 1

Grub sees whatever drives the BIOS sees; apparently it does not do any device detection on its own (which is why is as reliable as it is). Only one of the drives is visible in the BIOS as a boot target, so that would need to be resolved in the RAID config somehow.