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iridium_cluster:testnodes

Interactive access to the cluster: Iridium Cluster Testing nodes

Q: Why do I need this?
A: You need this if you want to test your code on some powerful machine.

The cluster has two testing nodes accessible from anywhere that should be used for testing your code.

hostname purpose
nptest-iridium.lunarc.lu.se test node for nuclear physics
pptest-iridium.lunarc.lu.se test node for particle physics and theoretical physics

They can also be used from time to time to host temporary courses.

They are meant for interactive access to the cluster, as opposed to the arc-iridium.lunarc.lu.se batch interface that can be used for batch submission of jobs. (link and explanation will come)

Accessing the Testing nodes

These nodes can be simply accessed via ssh. Ask Florido Paganelli or Pico for access credentials.

Examples:

ssh myusername@pptest-iridium.lunarc.lu.se

One can speed up access to the cluster by using the ssh config file (read here for detailed explanation). You can copy-paste the following into your .ssh/config file and modify it to your needs:


Particle physics and Theoretical Physics:

# access pptest-iridium
Host pptest-iridium
HostName pptest-iridium.lunarc.lu.se
User <username on iridium>
ForwardX11 yes

# directly access iridium node X (change X to your preferred node!)
Host iridiumnX
User <Username on iridium>
ForwardX11 yes
ProxyCommand ssh -q pptest-iridium.lunarc.lu.se -W nX:22

Example: My username is guest03. In the template above, I would change all the <Username …> to guest03, and nX to n12.

then to login to n12 I will do:

ssh iridiumn12

And I will have to input 2 passwords: one for pptest-iridium and one for the node.

The number of passwords can be reduced if one uses a private/public ssh key pair.


Nuclear physics:

# access nptest-iridium
Host nptest-iridium
HostName nptest-iridium.lunarc.lu.se
User <username on iridium>
ForwardX11 yes

# directly access iridium node X (change X to your preferred node!)
Host iridiumnX
User <Username on iridium>
ForwardX11 yes
ProxyCommand ssh -q nptest-iridium.lunarc.lu.se -W nX:22

Example: My username is guest03. In the template above, I would change all the <Username …> to guest03, and nX to n12.

then to login to n12 I will do:

ssh iridiumn12

And I will have to input 2 passwords: one for nptest-iridium and one for the node.

The number of passwords can be reduced if one uses a private/public ssh key pair.


Setup the work environment

Administrators provided scripts for quick setup of your work enviroment. Just execute the command in the column Script to run at the shell prompt, or add it to your .bash_profile file so that is executed every time you login.

:!:NOTE: do NOT add these scripts to .bashrc as suggested previously or you will not be able to rsync/scp. Contents of .bashrc are NOT supposed to generate output, but unfortunately some of these scripts do.

:!: NEW! 20150923 :!: All the environments should be enabled using modules. This will also work with the batch system. The previous solution didn't. Please update your scripts.

Environment Commands to run Description
List existing environments
module avail
Will show a list of available environments. To enable one, execute the command
module load <name of environment>

More info on modules on http://modules.sourceforge.net/

ATLAS Experiment environment
module load enableATLAS;
setupATLAS
Will setup all the needed environment variables for ATLAS experiment, and present a selection of other environments that the user can setup.

Keeping your session alive and your work running even if you disconnect

The cluster offers you various tools, among these Screen and the usual nohup command to detach from terminal output.

However, I personally suggest a tool called byobu, that is essentially Screen or Tmux on steroids. You can read about it here: https://help.ubuntu.com/community/Byobu

Local disk space on the test nodes

Every node has a local /tmp temporary disk space that can be used for computations. The contents of such space will be deleted regularly. Users can put any sort of data there. Currently the space available is 300GB.

iridium_cluster/testnodes.txt · Last modified: 2015/09/25 10:42 by florido