@Danp
Thank you for your replies. I deeply appreciate your support!
I have clearly not read the documentation good enough, not having caught that 8.3 is not released for production yet. Mea culpa!
Pro support:
I am not earning enough money on these servers to carry the full 8.000 USD extra cost per year. I have sent an e-mail to Vates previously and again today asking if they will give me a discount to help me get this business up and running. If I can get this afloat then I hope to bring much more income to both vates and my employer.
Being an old IT-consultant I believe in paying for products and support. I do want to support Vates in its development of XCP-ng.
Being the only one among my colleagues working with this, having spent many evenings and nights on this project, I have longed for Pro Support. But my employer is not a wealthy company. Wanting to spread the risk on several servers instead of gathering all VMs (eggs) on one server (one basket) we will have to pay a lot more with Vates' pricing structure of 1000USD per server. We can not - so far - carry the cost of large proper servers with vast amounts of RAM to host many VMs on which would reduce the Vates cost.
If i lose money then my employer will terminate the project.
If I can pay to have someone connect to the host to fix the problem then I will gladly do so.
Reboot to apply updates: I understood as much. I restarted only one server first, and when that failed to load VMs I did not dare to restart the remaining ones. The VMs on those work fine, for now.
I have shut down XCP-ng-005 completely. All the way until only the on/off switch could start it up again.
To get the VMs running again:
Is it "trivial" to downgrade a 8.3 host to 8.2 without ruining the VMs?
Or will I have to export VMs from a 8.3 server to a 8.2?
(Is a VM image backwards compatible?)
I fear doing this since I've had lots of problems moving VMs between hosts using XO. It has worked "50% of the time". Can you recommend a "howto" with commands I can type to copy the VMs more reliably to USB media, and import them in to a 8.2 host?
I am now cobbling together a new server from old parts, that I hope will be able to host the VMs temporarily until I can install 8.2 on the old one and move the VMs back.