The XFEL partitions serve for operation and simulations for the XFEL accelerator at DESY. Not to be confused with the European XFEL!° Talk to the M admins or XFEL team if you believe you should have access but don't.
The XFEL resources are "divided" into three partitions:
- The xfel-op partition. It's a highest priority partition. Jobs in this partition will immediately cancel any jobs in the all, xfel-sim or xfel-guest partition using the same nodes!
- The xfel-sim partition. It's a high priority partition. Jobs in this partition will immediately cancel any jobs in the all or xfel-guest partition using the same nodes!
- The xfel-guest partition. It's a regular priority partition combining all XFEL and PETRA4 resources. Jobs in this partition will terminate jobs in the all partition (like on any other partition). Jobs in the xfel-guest partition will be terminated by any jobs in the xfel-op, xfel-sim or petra4 partition using the same nodes.
Interactive Login Nodes
There are no login nodes associated with the XFEL resources in Maxwell.
- ssh max-display.desy.de: will connect you to one of the display nodes. FastX might your better choice. Please have a look at the Remote Login and the FastX documentation.
- ssh max-wgs: will connect you to the generic login node.
- Please note: max-display.desy.de is directly accessible from outside. All other login nodes can only be reached by first connecting to bastion.desy.de.
Login nodes are always shared resources sometimes used by a large number of concurrent users. Don't run compute or memory intense jobs on the login nodes, use a batch job instead!
The XFEL Batch resource in Maxwell
As a first step login to one of the login nodes and check which Maxwell resources are available for your account using the my-partitions command:
If it says "yes" for partition "xfel" you are ready to go. If so you will also see a "yes" at least for partition "all". If not: get in touch with M admins! Let's assume that you've got the xfel-guest-resource. Same rules apply to the other xfel partitions/resources.
If you have an application, which is started by a script called my-application, and doesn't require a GUI, you can simply submit the script as a batch-job:
This works for any application smart enough not to strictly require an X-environment, matlab, comsol, ansys, mathematica, idl and many others can be executed as batch jobs. To make it more convenient you can add the SLURM directives directly into the script:
The email-notification will be sent to <user-id>@mail.desy.de. That should always work, so you don't actually need to specify an email-address. If you do, please make sure it's a valid address. For further examples and instructions please read Running Jobs on Maxwell.
If you think that it's much to complicated to write job-scripts or if you can't afford to invest the time to look into it: we are happy to assist. Please drop a message to email@example.com, we'll try our best.
Running interactive batch jobs
If you absolutely need an interactive environment, X-windows features like a GUI, there are options to do that in the batch environment. For example:
There are a few things to consider:
- Interactive jobs with salloc easily get forgotten, leaving precious resources idle. We do accounting and monitoring!
- Keep the time short: there is hardly a good reason to run an interactive jobs for more than the working hours. Use a batch job instead.
- Terminate allocations as soon as the job is done!
Other Maxwell Resources
Being member of XFEL-OP and maybe having access to the xfel-guest partition doesn't need to be the end of the story. If you have parallelized applications suitable for the Maxwell cluster you can apply for the Maxwell resource like everyone else on campus. Please send a message to firstname.lastname@example.org briefly explaining your use case. You can easily distribute your job over the partitions:
The partition will be selected from xfel-op OR maxwell OR xfel-guest OR all starting with the highest priority partition. So your job will run on the xfel-op partition if nodes are available, on the maxwell partition if nodes are available and finally on the all partition if none of the other partitions specified have free nodes. Keep in mind that you should however select the partition according to the type of work you are doing. And a job can never combine nodes from different partitions, so check the limits applying to partitions.