Multiple OOD nodes on a single cluster

Hi. We’re currently running OOD on a single login node. What are the implications of running it on multiple login nodes? E.g. if they’re behind a load balancer a user could end up hitting a different node when revisiting the load balanced URL. What does that mean in terms of them accessing already-running interactive sessions etc? I guess basically I’m asking does OOD store any state on the OOD server or is it all in the user’s $HOME?

many thanks (for help, and for OOD in general!)

Hi and thanks for the question.

The only way to get this to work is with sticky sessions. The information is in fact in the user’s $HOME directory so they would need to connect to the same login node to access running interactive sessions.

We don’t have any official docs on this, but there have been previous posts on Discourse about this that may help, this link might have what you are looking for to get going:

If not please post any questions you have as we are happy to help and interested in knowing how others have done this for their site for the community.

Thanks for the reply. Does this suggest that in fact the normal way is just to have a single OOD node (i.e. because generally this has been enough to support sufficient users)? I guess I was assuming it got run on every login node, but maybe that was a bad assumption?

Yes, most sites have a single OOD node. Here are OSC we have it on a modestly sized VM and we have 6,000+ active clients with hundreds accessing it at the same time during certain periods.