Based on the upgrade instructions in the Operations Guide (http://docs.openstack.org/trunk/openstack-ops/content/upgrades.html), it sounds like upgrading from one major release to another is fairly difficult. Is it possible to live migrate virtual machines between two different OpenStack clusters? My thought is if you could set up a second cluster, when a new major release becomes available you could set it up on this second cluster, do testing on it, and then migrate all VMs to it. Once done, the old cluster could then be reprovisioned with the next major release 6 months later, and so forth.

Hi DanielS, thanks a lot for your answer. I´ve been trying to do the Upgrade by following the "havana Release Notes" but no success. I have had a lot of errors in the Dashboard, some of the Services etc ... so I have decided to install "havana" from scratch. I´ll keep you posted about my findings. Thanks a lot.