Hello, One of our DC is a very small one, though quite critical. It's almost hyper converged : hosts are compute+storage, but the engine is standalone. It's made of : Hardware : - one physical engine : CentOS 7.1 - 3 physical hosts : CentOS 7.2 Software : - oVirt 3.6.5 - glusterFS 3.7.16 in replica-3, sharded. The goal is to upgrade all this to oVirt 4.1.1, and if possible also upgrade the OSes. At present, only 3 VMs here are critical, and I have backups for them. Though, I'm quite nervous with the path I have to follow and the hazards. Especially about the gluster parts. At first glance, I would go this way (feel free to comment) : - upgrade the OS of the engine : 7.1 -> 7.3 - upgrade the OS of the hosts : 7.2 -> 7.3 - upgrade and manage the upgrade of gluster, check the volumes... - upgrade oVirt (engine then hosts) But when upgrading the OSes, I guess it will also upgrade the gluster layer. During this upgrade, I have no constraint to keep everything running, total shutdown is acceptable. Is the above procedure seems OK, or may am I missing some essential points? Thank you. -- Nicolas ECARNOT