New computing cluster in Koenigstrasse¶

Introduction¶

Since January 2022 we have a new computing cluster which is installed int he server room of the physiscs department at Koenigstrasse. Temporarily attached to the cluster is a 10TB disk for processing. We are currently (17th March 2022) waiting for a large amount of storage (40TB) which will then replace this temporary solution.

Hardware¶

• there are in total 8 compute nodes avalable;
• the compute nodes are named "usm-cl-bt01n[1-4]" and "usm-cl-bt02n[1-4]";
• each node has 128 cores;
• each node has 500Gb available;

Login¶

• public login server: login.physik.uni-muenchen.de;
• Jupyterhub: https://workshop.physik.uni-muenchen.de;
• both the server and the Jupyterhub require a two-factor-authentication with your physics account pwd as the first authentication. Then you can use a smartphone app like Google Authenticator (or any other app that generates time-based one-time-passwords). The app needs to be registered here: https://otp.physik.uni-muenchen.de, it is there called a soft-token.

Graphic Remote Login¶

A graphical remote login from outside the LMU network require a VPN connection. From June 2022 the only VPN connection is provided by eduVPN. After establishing a VPN connection the login is then done with X2GO as explained here. I was pointed to using the following logins:

• cip-sv-login01.cip.physik.uni-muenchen.de
• cip-sv-login02.cip.physik.uni-muenchen.de

but I am assuming the connections for Garching work as well. X2GO opens a KDE desktop, and of course the machine can connect to our cluster.

Processing¶

• as on our local cluster "slurm" is being used as the job scheduling system. Access to the computing nodes and running jobs requires starting a corresponding slurm job;
• the partition of our cluster is "usm-cl";
• from the login node you can start an interactive job via "intjob --partition=usm-cl" (additional slurm arguments are accepted as well);
• I created a python script which provides information on our partition (which jobs are running on which node, the owner of the job and so on);
• I have also put together a rather silly slurm script which can be used as a starting point;
• note that it is possible to directly "ssh" to all nodes on which one of your batch jobs is running. This can help to supervise the processing;

Disk space¶

• users can create their own disk space under "/project/ls-mohr/users/" such as "/project/ls-mohr/users/martin.kuemmel";

Installed software¶

We use a package manager called spack to download and install software that is not directly available from the linux distribution. To see what is already installed, do the following on a computing node:

• "module load spack"
• "module avail"

Adding more software is not a problem.

Euclid processing on the cluster¶

While OS, libraries and setup is different from EDEN-?.?, it is possible to load and run in an EDEN-3.0 environment using a container solution. The cluster offers singularity as a container solution. While singularity is not officially supported in Euclid, it is being used in a limited role, and singularity is able to run docker images, which is the supported container format in Euclid. To work in an EDEN-3.0 on the new cluster you need to get the docker image doing:

• load singularity via:
  

    $ module load spack
    $ module load singularity

  Note that the singularity version which is directly available on the computing nodes at "/usr/bin/singularity" does not work. The correct version loaded via the modules is at "/software/opt/focal/x86_64/singularity/v3.8.1/bin/singularity".
• it is recommended to move the singularity cache to somewhere under "/scratch-local", e.g. via:

  $ mkdir -p /scratch-local/$USER/singularity
  $ export SINGULARITY_CACHEDIR=/scratch-local/$USER/singularity

  On the default cache location "/home/$HOME/.cache/singularity" there are problems deleting the entire cache when leaving singularity.
• pull the Euclid docker image via:

  singularity pull --docker-login docker://gitlab.euclid-sgs.uk:4567/st-tools/ct_xodeen_builder/dockeen

  With the gitlab credentials the docker image is stored in the file "dockeen_latest.sif"

The docker image can be run interactively:

$ singularity run --bind /cvmfs/euclid.in2p3.fr:/cvmfs/euclid.in2p3.fr --bind /cvmfs/euclid-dev.in2p3.fr:/cvmfs/euclid-dev.in2p3.fr <path_to>dockeen_latest.sif

It is also possible to directly issue a command in EDEN-3.0:

$ singularity exec --bind /cvmfs/euclid.in2p3.fr:/cvmfs/euclid.in2p3.fr --bind /cvmfs/euclid-dev.in2p3.fr:/cvmfs/euclid-dev.in2p3.fr <path_to>dockeen_latest.sif  <command_name>

In both cases the relevant EDEN environment must first be loaded with:

$ source /cvmfs/euclid-dev.in2p3.fr/CentOS7/EDEN-3.0/bin/activate

Information on the usage of singularity in Euclid is available at the Euclid Redmine.

Support¶

Support is provided by the IT support (Rechnerbetriebsgruppe) of the LMU faculty of physics with the helpdesk email: helpdesk@physik.uni-muenchen.de. Please keep Joe Mohr and me (Martin Kuemmel: mkuemmel@usm.lmu.de) in the loop such that we can maintain an overview on the cluster performance.