Let's imagine CUCM 6.1(x) cluster with x1 PUB & x2 SUBs. All is up and running.
One day the PUB is damaged UNRECOVERABLY (you know, unspecified hardware problem).
Also there is no DRS (Disaster Recovery System) has been configured earlier and we have no backups.
All we have after this accident are x2 Subscribers.
What are all possible solutions to restore somehow our PUB server ?
If this ever hit (yikes!) you would be forced to re-build the Publisher from scratch. CCM 6.x and 7.x has the same design considerations as before when it comes to the Single Publisher with multiple Subscriber setup. My understanding is that Cisco is working on a method to promote a Sub to Pub for Disaster recovery purposes, but this has not yet been released. Soon I hope :)
Hope this helps!