HPC @ Uni.lu

High Performance Computing in Luxembourg

Migration From Gaia or Chaos to Iris

Below you will find a selection of links to relevant documentation and general guidelines how to migrate your workflows and data from the Gaia or Chaos cluster to Iris.


The scheduler on the Iris cluster is different from Chaos and Gaia. Chaos and Gaia use OAR, while Iris uses SLURM.

If you are using launcher scripts, either written yourselves or provided by us, you will need to adapt any #OAR directives to the corresponding #SBATCH ones. You can find updated versions of the ULHPC launcher scripts in the Git repository.


The software provided through the modules system is the same on all clusters.

If you installed/compiled software yourself you need to reinstall/recompile them on Iris. Iris uses a different operating system and likely dependencies and libraries are slightly different.


The best way to transfer larger amounts of data between the clusters is by using rsync from one access node to the other. Make sure you have set up SSH keys to be able to access one cluster from the other.

You can use the following command in your home directory ($HOME) on the Gaia cluster to transfer it’s contents to a directory named gaia_home in your home directory on Iris:

rsync --bwlimit=10m --rsh='ssh -p 8022' --exclude="/.local" --exclude="/.cache" -avzP . access-iris.uni.lu:~/gaia_home/

Since the transfer might take a long time, you can use the tool screen to keep the transfer running even when your SSH connection get’s disconnected.

If you have a lot of small files consider packing them into one tar.gz archive, since this will speed up the transfer significantly.

If you need to migrate data around 10 TB or more or a big number of files, please contact us.

Operating system

Be aware that Gaia and Chaos use Debian as their operating system, while Iris runs on CentOS.