The last two times I applied a CUM, the IPL did not complete because of false hardware errors. I was told by IBM that the microcode must have "gotten confused".
I had to manual IPL from the B side which worked fine, then reIPL unattended to actually get the PTFs to apply. There was never any hardwarre problems nor were any errors logged. My question - should I be pursuing this further with IBM or could it really just be confused microcode?