A word about running a persistent session
Key point: If you use a persistent session (e.g. tmux or screen), you must log in to a specific login node to reattach to an old session.
If you use Hoffman2 cluster regularly, you may consider creating a persistent session on one of the login nodes using screen or tmux.
Your local computer (laptop or desktop) may be rebooted from now and then, but the login nodes are rarely rebooted
$ ssh login2 uptime
21:59:56 up 42 days, 2:43, 62 users, load average: 1.68, 0.92, 0.65
One can create persistent session using screen or tmux on the login nodes, and reconnect to it in the next login so that you don’t have to repeatedly set up your environment.
But there are multiple login nodes. When you ssh me@hoffman2.idre.ucla.edu, you are assigned an arbitrary login node, which may not be the one that your screen/tmux session was on.
If your persistent session is on one of the login nodes, you must always ssh specifically to that login node in order to re-attach to your tmux/screen session, e.g.
ssh me@login2.hoffman2.idre.ucla.edu
Typically you would submit jobs or launch interactive jobs from the persistent screen/tmux session, instead of running compute-intensive tasks directly on the login nodes.
If you are not using screen or tmux, don’t worry. Just submit jobs, batch or interactive, from the terminal of your login session.