Accessing the System

Let’s Go!

To access HPC Wales supercomputers via the command line, you must use a terminal emulator, which connects your local keyboard and screen to the remote system. This uses a protocol called “Secure Shell”, or “SSH”; this is available as standard with a Linux workstation, but requires a program to be downloaded and installed with Microsoft Windows.
The HPC Wales infrastructure consists of a number of distributed compute clusters. Each of these clusters has its own ‘Login Nodes’, which enable you to execute and manage jobs on that particular cluster.
When you are accessing the systems from the wider Internet, then you must first login to an ‘Access Node’. Access Nodes provide a security hardened entry/exit point to HPC Wales’ services -think of them as the gate keepers to the private HPC Wales network. Once you have successfully logged in to an Access Node, you can move freely to any of the cluster Login Nodes.
If you are accessing from a partner University Campus network you may be able to connect directly to the Cluster login nodes. In that case, please see the ‘University Access to HPC Wales Systems’ companion document which can be found on the HPCW User Portal.

Logging in from Windows

In order to log in to HPC Wales, enter “login.hpcwales.co.uk” into the “Host Name (or IP address)” box; you may wish to save this for reuse, in which case also enter a name in the “Saved Sessions” box, and hit the “Save” button.
After entering the address of the machine you wish to log into (“login.hpcwales.co.uk”), click on the “Open” button to connect to the HPC Wales cluster. You may be asked to accept a security certificate – this will happen the first time you log into the cluster from a machine.
Accept the certificate, and you will be linked to an HPC Wales Access Node – your first point of entry. A screen will pop up akin to this:
You are now set to log in – now enter your username, in the form “ John.Doe ” (Usernames are not case sensitive), such as:
Please skip the next section “Logging in from Linux” and proceed with section “Entering your password”.

Logging in from Linux

Linux has SSH (“Secure Shell”) built – in, so you should not need to install ssh manually. To log in to HPC Wales, simply start a terminal and enter:

ssh John.Doe@login.hpcwales.co.uk

Where you should replace “John.Doe” with your username. On first logging on from a machine, you will be asked to confirm the secure certificate associated with HPC Wales Access Nodes; please confirm “yes”, such as:

[~]$ ssh John.Doe@login.hpcwales.co.uk
The authenticity of host 'login.hpcwales.co.uk (XXX.XX.XX.XXX)' can't be established RSA key fingerprint is 20:XX:6d:XX:be:XX:05:XX:ed:XX:XX:XX:XX:XX:XX
Are you sure you want to continue connection (yes/no)?
yes

You will then proceed to be asked for your password, and can continue with the next section on logging in (which is common to both Linux and Windows).

Entering your Password

Your password will now be requested; please enter the initial temporary password you have been provided with. You will be requested to immediately change this temporary password, so please follow the instructions. Note that you must re-enter the temporary password before entering your new password (you will be asked to enter it twice for confirmation).
There are specific password rules; it must be 8 or more characters, and must have three of the four following characteristics:
  • Upper case letter
  • Lower case letter
  • Number
  • Symbol e.g. $%?!
If you fail to adhere to the rules, the system will reject your password.
Once you are logged in successfully, you will see text displayed similar to the following:

--------------------
HPC Wales Login Node
--------------------

Cyfrifiadura Perfformiad Uchel biau'r system gyfrifiadur hon.
Defnyddwyr trwyddedig yn unig sydd a hawl cysylltu a hi neu
fewngofnodi. Os nad ydych yn siwr a oes hawl gennych, yna
DOES DIM HAWL. DATGYSYLLTU oddi wrth y system ar unwaith.
This computer system is operated by High Performance Computing Wales.
Only authorised users are entitled to connect or login to it.
If you are not sure whether you are authorised, then you
ARE NOT and should DISCONNECT IMMEDIATELY.

---------------------Message of the Day------------------------------

No service problems reported at this time.

---------------------------------------------------------------------

You are now logged into the HPC Wales Network, please type 'hpcwhosts' to
get a list of the site cluster login servers.

[john.doe@cf-log-103 ~]$

You are now at the command prompt of an Access Node of HPC Wales.

Accessing Cluster Login Nodes

HPC Wales provides a distributed network of computational resources, divided as follows:
  • Two Hub Facilities for Large Scale/Parallel Computation at Cardiff and Swansea
  • One Tier 1 Medium Scale Computation at Bangor
To access one of the compute clusters if you type “hpcwhosts”, you will see a list of the available cluster login nodes, reachable via the distributed network:

[john.doe@cf-log-103 ~]$ hpcwhosts
HPC Wales Clusters Available
Phase    System Location & Type             Login Node(s)
------------------------------------------------------------------
1        Cardiff High Throughput            cwl001   cwl002   cwl003
1        Bangor Medium Processing           bwl001   bwl002
2        Swansea Capability/Capacity/GPU    ssl001   ssl002   ssl003
2        Cardiff Capacity/GPU               csl001   csl002
type: ssh and then one of the above nodes to access a site.
[john.doe@cf-log-103 ~]$ ssh cwl001

By following the displayed instructions, you will access a login node of one of the compute clusters (the Cardiff HTC system in the above example); from here, you can now write code, compile code, and submit jobs to the cluster for processing.

Tip: Note that with the shell command line, you can use the left and right cursor keys (arrow keys) to move the cursor around the current line of text at the command prompt and edit it – to remove any mistakes or change your mind. Similarly, pressing the up or down arrow will bring back the previous command you typed. Pressing the up arrow repeatedly will show older and older commands – whereas the down arrow will bring you back to the last command you typed, or press it again – back to a blank line ready for you to start a new command.

For next steps, please see the HPCW User Portal.