GViking is a multidisciplinary GPU cluster, supporting a broad spectrum of research needs, free at the point of use to all University of York researchers. GViking has been set up to be similar to the Viking cluster. As such it uses the following;

Slurm to schedule your workloads
EasyBuild and Lmod to allow you to load your applications.
CentOS Linux

If you wish to learn more about Slurm and how to load your applications using the module system see the following wiki pages;

Slurm

/wiki/spaces/RCS/pages/39167429

/wiki/spaces/RCS/pages/39159178

If you are coming to GViking from Viking please note that GViking does not support the #SBATCH --account option in job script files, please remove this line for use on GViking.

Below we have provided details on the hardware, how to login and the partitions available.

GViking Account Creation

You will need to create an account on Viking before being able to login. The instructions on how to do this are below.

Click here to expand...

Before logging into gViking please ensure your project supervisor fills in this form to request a project code.
The user then needs to fill in this form to request an account once they have a project code.
Accounts should take no longer than 24 hours to be created. You will receive an email on creation of your account.

Login into GViking

GViking has a Linux Operating system therefore how you access GViking will depend on what your operating system is on your local machine.

We will break down the different options here.

Before You Login

If you have not changed your IT Services password since August 2013 then you must do so before you will be able to login. All user password changes are managed via the My IT Account web page. Click on the Password Management (IDM) link in the Manage Your Password field to change your password. You may be given the option to 'synchronise' your password; please use this option if you do not want to change your password. The password change (or synchronisation) may take a few minutes before it is visible to the servers.

Accessing GViking off campus

To access the Viking off campus you can either use the Virtual Private Network - VPN or the SSH gateway service (registration required). The instructions below should work if you log on through the VPN; the SSH service works slightly differently.

MacOSX

Access from a Mac

Go to the Finder on your Mac, find Applications, open the Utilities folder in Applications and then start the Terminal app from the Utilities folder. (You may wish to add Terminal to your Dock.) Then type the following, using your university username (abc123). You do not need to type the $; this is an example of a prompt, which tells us the terminal is ready for us to type something. You should see something similar when you open Terminal, though it may be a bit longer (it may show your username for example). Just type anything from after the $.

[bash-4.1]$ ssh -X abc123@gviking.york.ac.uk

Linux

Access from a UNIX server or desktop

To login from a terminal emulator, use the following command:

[bash-4.1]$ ssh abc123@gviking.york.ac.uk

where abc123 is your IT Services username. You will be prompted for your IT Services password. Please note, X11 forwarding will only work on the GViking login node, which means that you won't be able to run graphical applications e.g. MATLAB on the GViking compute nodes using X11 forwarding.

If you require X forwarding, type:

[bash-4.1]$ ssh -X abc123@gviking.york.ac.uk

Hardware

GViking consists of:

Login nodes

Login node (no GPUs) 1 core

The login node is a single core VM. It does not have a GPU. If you wish to test your code we recommend using the test partition or the interactive partition if you need to use a GUI.

GPU nodes

gpu01.york.ac.uk: Asus ECS8000G4 with 8 x A40
gpu02.york.ac.uk: Asus ECS8000G4 with 8 x A40
gpu03.york.ac.uk: Asus ECS8000G4 with 8 x A40
gpu04.york.ac.uk: Asus ECS8000G4 with 5 x A40.

Each server contains

2x Intel(R) Xeon(R) Gold 6240R CPU @ 2.40GHz (total 96 cores)
512 GB
2TB on node storage via /tmp

Fileserver

scratch: Intel server with 8x8TB SSDs to provide networked /scratch storage
44 TB scratch space. Not backed up.
When you login you will see two folders localtmp and scratch. Please use the scratch area for your datafiles.
Each user has a default 2TB quota limit. If you need more please contact itsupport@york.ac.uk.
Each GPU also has 1TB of /tmp space. If you use this please delete your data once you have finished processing.

Available partitions

Partition name	Max job time	Max number of jobs per user	Max running GPUs per user	Max running memory per user	Number of GPUs in partition	Additional Information
test	30 mins	2 running; 4 total	2 GPUs per user at any one time, minimum of 1 GPU per job	No limit	29	Partition for testing small jobs. Request using --partition=test in job script.
gpu	7 days	No limit	2	No limit	29	Default partition for everything. Max 2 GPUs
gpu_big	48 hrs	No limit	Up to 8	No limit	29	Partition for running jobs that require a larger number of GPUs. Users can request up to 8 GPUS. Need to request using --partition=gpu_big in job script. Please only request 8 if you need them. You can request 1-8 GPUs in this partition.
Interactive	4 hours	No limit	1	No limit	29	Partition for interactive jobs. This could be used for graphical work with the 8 hr queue limit set to mimic a working day. Need to request using --partition=interactive.

Support

If you need an application to be installed as a module or if there are other problems please contact itsupport@york.ac.uk in the first instance.

Virtual Desktops on GViking - from a Linux device

Starting and using a virtual desktop on GViking is slightly different to Viking but you can access the GPU node and harness it's power interactively. Below is a summarised list for each of the steps in the procedure with full examples further down. Please be sure to kill the virtual desktop session when you are finished. Only closing the windows will not actually end the virtual desktop and if left running they will take up the shared resources on GViking affecting other users. This guide currently describes only connecting from a Linux computer to GViking.

Create a session
Show the log in details
SSH port forward (locally)
Connect via VNC
Run program or
Start srun session from the virtual desktop
Set DISPLAY variables
Run GUI program
Kill the virtual desktop

1. Create the virtual desktop session

Firstly connect to GViking and from the command line start a new desktop session with:

flight desktop start

2. Show the log in details

You are prompted to type a command to show the log in details of the virtual desktop, we need to run this command. From the example above it is:

flight desktop show bac22487

3. SSH port forward

Locally, from a new local terminal session run the ssh command as prompted. In the above example I ran, but yours will be different:

ssh -L 5905:144.32.255.190:5905 nd996@gviking.york.ac.uk

This will forward a local connection over SSH to GViking and allow you to connect a VNC client to the virtual desktop. This local terminal needs to be kept open for the duration of the virtual desktop connection.

4. Connect with a VNC client

Using the other details from the output of Step 2. connect to the virtual desktop with a VNC client. On my Linux machine this is Remminia and in my example I typed localhost:5905 and ensured vnc was selected from the drop down menu.

When prompted enter the password provided from Step 2.

You will now be connected to the virtual desktop.

5. Run program

For quickly viewing or testing an application this is a good environment to work in. There is no GPU being used, everything is on the shared resource of the login node. Please remember to complete Step 9 to kill the session when you are finished. To use the GPUs please continue.

6. Start an interactive session

Once you are connected to the desktop session over VNC, X forwarding from a GPU node can be configured under an interactive job as follows, in this example we request an interactive job for just 15 minutes as a test. This can be a maximum of 4 hours:

srun -p gpu --gres gpu:1 -t 00:15:00 --pty /bin/bash

7. Set the DISPLAY variables

Once allocated, the DISPLAY environment variables must be set, as seen above:

ssh login1 DISPLAY=$DISPLAY xhost $(hostname -s)
DISPLAY=login1$DISPLAY

8. Load modules and run GUI applications

You can now load modules and run GUI programs from this terminal, utilising the GPUs for the allocated time. Please refer to the Viking modules page for general information.

9. Kill the virtual desktop session

It's important to kill off any unused virtual desktop sessions to stop any shared resources being taken up unnecessarily. Close down the Remminia window and then simply request a list of all running sessions from your GViking SSH terminal session and kill any that aren't needed.

flight desktop list

The identity is what we need to kill this session, like the following for this example:

flight desktop kill a5576e37

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