Hi All, OK, so after much reading of logs, Ansible files, blog posts, documentation, and much gnashing of teeth, glasses of bourbon, language to make a sailor blush, tears, blood, sweat, and various versions of "DOH!", I finally worked out what was wrong - what I did wrong - and so I'm putting it down here so that the next person who comes along with the same (or a similar) issue doesn't have to go through what I went through - and I'm including a couple of suggestions to the devs/doco writers which (I believe) would have stopped me from making my mistake in the first place. When I did my install I used the command: ~~~ hosted-engine --deploy --4 --ansible-extra-vars=he_ipv4_subnet_prefix=172.16.1 ~~~ I did this because we're running an IPv4 network and because the oVirt Engine needs to be on the 172.16.1.0/24 network - and that's what I thought the "he_ipv4_subnet_prefix" option did, and I was trying to let the deployment script know this in advance instead of having to discover this itself. Now that I've gone back over *all* the doco I realise that the "he_ipv4_subnet_prefix" option is *not* used for this purpose, but is instead used for the *temporary* ip address of the deployment engine when the default subnet of 192.168.222.0/24 is not available. Because I was specifying the 172.16.1.0/24 network (which is already in use) the deployment failed because it was attempting to create that network as a temporary network for the initial deployment. So yes, as I said, my fault - no question about that at all. Some suggestions: Although it is stated in the documentation - Installing oVirt As A Self-Hosted Engine Using The Command Line, section 2.3.2 (https://www.ovirt.org/documentation/installing_ovirt_as_a_self-hosted_engine...) - (I believe) it is not very clear what is happening here, so a "Note:" or some sort of statement explicitly stating what this is used for might be in order. For example, here is the note I made for our team in our internal documentation: ~~~ **Note:** he_ipv4_subnet_prefix=x.x.x: - This is a temporary network prefix if 192.168.222.0/24 (the default) is not available - this is ***NOT*** the final working subnet of the oVirt Engine. ~~~ I also believe - quite strongly, in fact - that having the entire deployment hidden behind the "black box" that is the Ansible deployment - while making things easy by automating the deployment - makes troubleshooting more difficult. I believe that if there was a definite "Step-By-Step" list of what was going on behind the scenes - perhaps as an Appendix to the documentation - then the mistake I made would have been a lot harder to make - ie if there was such a list then it would have been less likely to make the assumption I made. I'm thinking something along the lines of (and I am aware that what follows is not correct): ~~~ 1. Collect info - this is stored in "/path/file" temporarily. 2. Install Deployment VM. 3. Deployment VM creates internal bridge - this uses 192.168.222.0/24 by default but can be overridden by "he_ipv4_subnet_prefix". 4. Deployment Engine creates oVirt Engine. etc, etc, etc ~~~ Anyway, that's my feedback / suggestions / mea culpa / whatever. :-) Cheers Dulux-Oz