Hi David, See my answers inline Regards, Maor ----- Original Message ----- Engine 3.0 should support backward compatibility for ovirt 3.4. You can verify that on the node be executing the following command : "vdsClient -s 0 getVdsCaps" (-s for secure), There, you should see a supportedENGINEs list. no, but take in consideration that after upgrade, those hosts might get into non-operational state, in case VDSM version should be upgraded also. There is no limitation of doing that, it's simply a question of the architecture you want to support. Separating the engine from the Storage server, might be useful to make it more high available.