Connecting to Zeus HPC

Connecting in console with secure shell (ssh)

The (almost) only way to connect to HPC is to connect via secure shell (ssh) to the headnodes (zeus.coventry.ac.uk, zeus2.coventry.ac.uk, zeus3.coventry.ac.uk, zeus.coventry.ac.uk ) with your HPC user name and password (different to the University ones, see Request access to HPC).

To do that you will need ssh client software. The possibilities are:

PuTTY ssh client, that can be downloaded and installed on your desktop PC from http://the.earth.li/~sgtatham/putty/latest/x86/putty-0.62-installer.exe. The documentation for using PuTTY can be found at http://www.chiark.greenend.org.uk/~sgtatham/putty/docs.html.
OpenSSH for Windows SSHWindows, installer for Windows can be found here: http://sourceforge.net/project/showfiles.php?group_id=103886&package_id=111688
If you are using Linux machine, you most probably already have ssh client utility (type “ssh -Y zeus.coventry.ac.uk” in the console to connect to e.g. zeus HPC)

Presuming you are installed PuTTY; start it form the Start menu, you will get this configuration window to set up a session; fill as in the example below (change pluto=> zeus though):
putty1

Hit “Save” and then “Open” to connect. Enter your username as asked in the appeared console window and your HPC password.

Connecting to the Desktop of HPC with VNC session

You can bring the desktop window of a headnode to your local machine remotely by using VNC connection.
If you never started VNC connection you have to start vncserver on one of the login nodes (you have to do it only once until you killed this vncserver session, so you can use the same session many times during months).

Start vncserver on HPC’s headnode

Now you need to start the VNC session on one of HPC’s headnodes (zeus…zeus). This is done by launching “vncserver” command. Still being logged into the headnode’s console, type:
```
vncserver -geometry 1280x800
```
which will start the desktop session (virtual desktop) as a background-running process with desktop size of 1280×800, which you can change, e.g. to match your local PC monitor’s resolution or even start vncserver without “-geometry…..” switch to have default size of the desktop (quite small).

If this is a first time you starting vncserver, you will be asked to create a password for this and all future vnc-sessions. You are free to choose any password you like, it will be used only for this and further vnc-connections. The password is NOT NECESSARY your HPC password (i.e. the one you use to connect to the HPC with ssh).

After all, as a result you must have something like (I used zeus to start it on):
```
[user@zeus]$vncserver -geometry 1280x800

New 'zeus.coventry.ac.uk:2 (aa3025)' desktop is zeus.coventry.ac.uk:2

Starting applications specified in /home/aa3025/.vnc/xstartup
Log file is /home/aa3025/.vnc/zeus.coventry.ac.uk:2.log
```
Which means that your remote desktop is started, its “vnc-address” is “zeus.coventry.ac.uk:2” (important “:2” bit here is vnc desktop number) and now you can connect to it from your local machine with VNC-client.

Connecting to the VNC Desktop you’ve just started on one of the headnodes

To connect to the VNC session you have just started on HPC you will need another bit of software on your local PC: VNC-client. There are few free ones you can download and install (RealVNC, TightVNC, TigerVNC). The best results in terms of speed of graphics gives TigerVNC, which can be downloaded from http://sourceforge.net/projects/tigervnc/files/ or look on W:ecstudenthpc folder.
After you installed it, launch it, it will bring up the dialog window asking for hostname and password. Enter the hostname: “zeus.coventry.ac.uk:2”. Note the last “:2” is important, this is the display number you want to connect to. You have it from the previous step (“starting vncserver”). Enter the password, the one you have chosen to be your VNC-connection password during the above steps.

As a result you must have remote desktop window showing the headnode’s Desktop:

vnc

You can work in that desktop session (hit F8 for “fullscreen” [here you will find that using correct “-geometry …” flag was useful] or Options), start whatever program on the headnode and leave it running. When you close the VNC window, the Desktop session and the programs you have started on the headnode are still running, so that you can connect to the same VNC-session Desktop many times later and continue whatever you were doing.

Next time it is not needed to create new VNC-session, you just need to connect again with TigerVNC to the same desktop, e.g. “zeus.coventry.ac.uk:2”. The actual VNC Desktop session will be destroyed only when you deliberately kill it (or the headnode has been restarted), from the command line it can be done as (within the same vnc-desktop or any other ssh-session):

vncserver -kill :2

Linux local machines

If you’re lucky enough to have linux local machine, all the programs you need for connection are usually already installed by default and you can use native Linux X11 server to run remote GUI applications on HPC via ssh-connection. To establish ssh-connection with X11 (graphics) support use ssh switch “-X” or “-Y”: