I apolagize in advance if this is miscategorized or already covered.

I am currently running Z7 with the latest updates on Ubuntu 10.04LTS which is now depricated. I am looking to upgrade to 12.04, obviously I do not want to disrupt my current installation (besides obvious downtime). It supports a small business that can afford 24 hours or so of downtime (although I hope this is avoidable). The instalation is contained on one dell poweredge 1850.

What steps should be performed? I have noted the Ubuntu directions, but are there any special proccesses that must occur within zimbra before I perform the upgrade? (There are seperate released for the two versions of ubuntu, so is it even possible?) Thank you.