In practice I think you usually get there. The most significant thing we learned from our first DR was that, left to itself, the vendor's backup routing left /etc well down the list. We almost ran out of time before it was restored. Having rewritten the backup to prioritise the directories we needed to boot, we could do that and then get the database restore running in parallel with everything else. I suspect the everything else that originally stood in the way of /etc was largely a huge stack of crud whose owners would have been prepared to defend it to the death.
Biting the hand that feeds IT
