[ovirt-users] troubleshooting node upgrade failures

I have a very standard three node HCI setup running the latest version of oVirt 4.2. I've been having some problems updating hosts, the last update that was released a few weeks ago would produce installfailed when updating hosts. I was able to resolve this by rebooting the host first then performing the update. I eventually got all three hosts updated. Fast forward to this week, a new update is available. I've updated engine successfully but first host, I put in to maintenance then updated and the install is failing. I've rebooted it twice and attempted update again but no go this time. What logs should I be looking at to determine what is causing the node update failures?