I have a call manager cluster with 3 servers(1 PUB + 2 SUB) running on 4.1(3). I am planning to upgrade to 6.1(3). I want to do PUB upgrade first. During the time when PUB is getting upgraded to 6.1(3) using DMA, call processing will be taken care of by other 2 SUB servers. If the upgrade of PUB fails the I want to revert to 4.1(3). Using disaster recovery disc, I can choose the windows pre install option to re-install. At this stage will the PUB pull the config from other 2 SUB servers or do I need to restore the old backup.