Comment (by Roland Haas):

It does seems as if a non-existent guarantee setting took the limit to be the guarantee. i have updated the settings and was able to start 2 notebooks at the same time.

The server will probably support ~6 concurrent notebooks (0.5 CPU for each plus 1 CPU for admistrative tasks). It has enough memory for that (8GB total, no swap allowed). To scale larger we would have to find out how to have the etkhub spin up new VMs as needed (which is probably can somehow do).

@Bill Gabella please try again (I have terminated one of my instances just to be sure).

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2234/trouble-in-the-tutorial-server