Logging In

Overview

Teaching: min
Exercises: min

Questions

• What is a command-line?

• How do I log in to the cluster?

• How is a cluster structured?

Objectives

What is a cluster?

Brief cluster description, including:

• Typical HPC cluster
• Distributed system

Basically, anything where you log in at a single entry point and then your work is run on other execute points has the potential to be a large scale system.

Logging in

To log into the head node, you will need the name of the node, called the hostname and a specific username and password. This information can be given to a log-in protocol called ssh or “secure shell”, which establishes a secure connection for you between your computer and the head node, and creates a shell session on the head node.

On a Mac or Linux system, you can use ssh via the “Terminal” application to log in. The structure of an ssh login looks like this.

$ ssh username@hostname

There are multiple programs to connect to remote servers for Windows. One easy to use option is “PuTTy”, which can be downloaded here. When you open the Putty executable (putty.exe), you should see a screen like this:

See the field where you should enter the hostname of the head node.
You should use Port 22 and connect using “ssh” – these are usually the defaults.
After you click “connect” you will be prompted to fill in your username and password.

Logging in

Based on the information given by the instructor, log in to the system that you’ll be using for this workshop.

Key Points

• A cluster is many small computers rather than one large computer

• The login (head) node is the entry-point to the cluster

• A command-line is one way to talk to a computer and make it do things

• A secure shell client is a program that lets us log-in to other computers and run a command-line on them