I currently have a 3 server cluster all running Ubuntu 12.04 with the master server dealing with the DNS, emails and such. However we have started having issues with the email server side (postfix and courier) i have put it down to the upgrade from 11.10 and also because of the broken sasl. I wish to do a reimage and follow the guide for perfect install with dovecot instead of courier. Does anyone know what backups i would need to do and how i would go through the process to make it ready for the reimage. Once im at that point im ok i just need a little guidence to get to that point.