You just don't know how difficult that is becoming..
Why just yesterday, I upgraded the OS on a guest partition on an IBM system i. The primary was at 6.1 and the guest was going to 7.2. Cleared this through IBM support. I needed to restore some fixes via tape to the guest so we moved (virtually) a tape adapter over to the guest, did the restore, and left it there. After the upgrade, we moved the adapter back to the primary. Then we couldn't get the tape drive to work. Had to call IBM to replace the adapter. I'm thinking that the guest updated the firmware on the adapter to 7.2 levels and then the 6.1 OS on the primary just couldn't deal with it and gave up. It also could be that the fixes on the primary aren't current enough to support the new firmware upload. So lesson learned, if you are moving adapters on partitions, move them back before you update the partition in question.
Of course, things like this make me crazy and annoyed.