OK I see. You’re trying to use linux host adatper? With that adatper, yes you need
ssh_hosts because it works over SSH. It’s not the PBS batch scheduler, it’s just sshing to a login node and starting processes.
So: If you’re trying to use this adapter, then you’ll need host based authentication. You need this to allow users to ssh freely from the OnDemand server to your login hosts without being prompted for passwords. You could require everyone generate ssh keys without passwords, but that seems over-burdensome on your users.
If you’re not trying to use this adapter, if you want to schedule though the PBS server, then you don’t need
submit_host if you have all the PBS binaries installed and setup on the OnDemand server.
To sum up and for clarity:
submit_host is required for the
linux_host adapter because it works over SSH and needs to know where to ssh into. Because this host is likely a virtual name, it also needs a list of
ssh_hosts to poll to get the status of the “job” it submitted (“job” here in quotes because it just shelled somewhere and
tmux backgrounded a process group).
submit_host for all other adapters in 1.8 and beyond is when a site doesn’t want to install a batch schedulers libraries on the OnDemand server. So instead of running
squeue or any other PBS/Slurm/Torque/etc command on the OnDemand server; we instead ssh into a login node an run the command there where all the libraries are installed and configured.