Connecting to ARCHER2 and transferring data

Overview

Teaching: 20 min
Exercises: 20 min

Questions

• What can I expect from this course?

• How will the course work and how will I get help?

• How can I give feedback to improve the course?

• How can I access ARCHER2 interactively?

Objectives

• Understand how this course works, how I can get help and how I can give feedback.

• Understand how to connect to ARCHER2.

Purpose

Attendees of this course will get access to the ARCHER2 HPC facility. You will have the ability to request an account and to log in to ARCHER2 before the course begins. If you are not able to log in, you can come to this pre-session where the instructors will help make sure you can login to ARCHER2.

Connecting using SSH

The ARCHER2 login address is

login.archer2.ac.uk

Access to ARCHER2 is via SSH using both a time-based one time password (TOTP) and a passphrase-protected SSH key pair.

Passwords and password policy

When you first get an ARCHER2 account, you will get a single-use password from the SAFE which you will be asked to change to a password of your choice. Your chosen password must have the required complexity as specified in the ARCHER2 Password Policy.

The password policy has been chosen to allow users to use both complex, shorter passwords and long, but comparatively simple passwords. For example, passwords in the style of both LA10!£lsty and horsebatterystaple would be supported.

SSH keys

As well as password access, users are required to add the public part of an SSH key pair to access ARCHER2. The public part of the key pair is associated with your account using the SAFE web interface. See the ARCHER2 User and Best Practice Guide for information on how to create SSH key pairs and associate them with your account:

• Connecting to ARCHER2.

TOTP/MFA

ARCHER2 accounts are now required to use timed one-time passwords (TOTP), as part of a multi-factor authorisation (MFA) system. Instructions on how to add MFA authentication to a machine account on SAFE can be found here.

Data transfer services: scp, rsync, Globus Online

ARCHER2 supports a number of different data transfer mechanisms. The one you choose depends on the amount and structure of the data you want to transfer and where you want to transfer the data to. The two main options are:

• scp: The standard way to transfer small to medium amounts of data off ARCHER2 to any other location.
• rsync: Used if you need to keep small to medium datasets synchronised between two different locations

More information on data transfer mechanisms can be found in the ARCHER2 User and Best Practice Guide:

• Data management and transfer.

Installation

For details of how to log into an ARCHER2 account, see https://docs.archer2.ac.uk/quick-start/quickstart-users/

Check out the git repository to your laptop or ARCHER2 account.

$ git clone https://github.com/EPCCed/2025-05-19-MO-Fortran-intro.git
$ cd 2025-05-19-MO-Fortran-intro

Within the repository, the code we will use is located in the exercises directory. The default Fortran compiler on ARCHER2 is the Cray Fortran compiler invoked using ftn. For example,

$ cd exercises/01-hello-world
$ ftn example1.f90

should generate an executable with the default name a.out. If you are working on another machine, you should invoke the correct compiler e.g. gfortran.

Each section of the course is associated with a different directory, each of which contains a number of example programs and exercise templates. Answers to exercises generally re-appear as templates to later exercises. Miscellaneous solutions to some of the larger problems also appear in solutions subdirectories.

Not all the examples compile. Some have deliberate errors which will be discussed as part of the course.

Course structure and method

Rather than having separate lectures and practical sessions, this course is taught following The Carpentries methodology, where we all work together through material learning key skills and information throughout the course. Typically, this follows the method of the instructor demonstrating and then the attendees doing along with the instructor. There are some larger exercises we will start working on at the end of day one.

There are many helpers available to assist you and to answer any questions you may have as we work through the material together. You should also feel free to ask questions of the instructor whenever you like. The instructor will also provide many opportunities to pause and ask questions.

Key Points

• We should all understand and follow the ARCHER2 Code of Conduct to ensure this course is conducted in the best teaching environment.

• ARCHER2’s login address is login.archer2.ac.uk.

• You have to change the default text password the first time you log in

• MFA is mandatory in ARCHER2