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Access and Login

On this Page

  • Why a connection is refused, and the VPN requirement
  • SSH keys that do not work
  • A login that fails or hangs after your password
  • Telling the login node and compute nodes apart

Why Can I Not Connect to the Cluster?

The most common reason is the network you are on. SSH to aoraki-login.otago.ac.nz is only reachable from the University network — either on campus, or connected to the campus VPN. From home without the VPN the connection will simply time out.

Work through these in order:

  1. Are you on campus or on the VPN? If not, connect to the VPN and try again.
  2. Do you have an account? Cluster access is not automatic with a University account. See How do I get an account?
  3. Is it just you? https://ondemand.otago.ac.nz does not need the VPN. If OnDemand works and SSH does not, the problem is your network or SSH configuration rather than your account.
  4. Is there maintenance on? Check the Announcements section for scheduled outages.

If none of those explains it, email rtis.support@otago.ac.nz with the exact error message and the output of ssh -v <username>@aoraki-login.otago.ac.nz.

Why Am I Still Asked for a Password After Setting Up an SSH Key?

Your key is not being offered, or the server is not accepting it. In order of likelihood:

  • The key was never copied to the cluster. Run ssh-copy-id, or register it through OnDemand — see Setting up SSH key access.
  • You are connecting as the wrong user. Use your University username, not your email address. (OnDemand is the opposite: it wants the full email address.)
  • Your home directory or ~/.ssh has permissions that are too open. SSH refuses keys in that case. On the cluster, chmod 700 ~/.ssh and chmod 600 ~/.ssh/authorized_keys.
  • Your home directory is full, so authorized_keys could not be written. See below.

ssh -v will show which keys your client offered and how the server responded.

My Login Fails or Hangs Straight After My Password. What Is Wrong?

Check whether your home directory is full. Your shell has to write to your home directory as it starts, so at the hard quota a login can hang, drop straight back out, or land you at a -bash-5.1$ prompt with none of your usual settings.

The quickest way to confirm it is to log in to OnDemand and use the Files app, which will show your home directory even when a shell login will not complete.

See Storage and Quotas for what usually fills a home directory and how to clear it. If you cannot get in at all, email rtis.support@otago.ac.nz — we can free enough space to get you back to a working shell.

How Do I Get an Account?

Cluster access is provisioned separately from your University account. Fill in the account request form; requests are normally processed within one business day and you will be emailed when it is ready.

Storage allocations are requested separately again — see Storage Request.

Should I Use SSH or OnDemand?

Both reach the same cluster, the same files and the same scheduler. Use whichever suits the task.

SSH OnDemand
Needs the VPN off campus Yes No
Best for scripting, sbatch, rsync, anything repeatable notebooks, RStudio, graphical software, browsing files
Survives a dropped connection No, unless you use tmux Yes — sessions keep running
Setup SSH key, one time None

Which Machine Am I On?

Terminal

hostname

aoraki-login is the login node — shared by everyone, and not where your analysis should run. A name like aoraki07 or aoraki-g01 is a compute node, which means you are inside a Slurm allocation.

Why Was My Program Killed as Soon as It Started?

If you were on the login node, it was probably killed for using too much of it. Each user is limited to 8 CPUs and 60 GB of memory there, and exceeding that triggers a warning email and possible cancellation.

The login node is for editing scripts, moving data and submitting work. To actually run something, ask Slurm for an allocation — see Interactive Sessions from the Command Line or the Slurm Quickstart, and Login Node Usage for what is and is not reasonable there.

What's next?