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guide:how_to_get_support

Contact & Help


Need help running your job on the cluster? Need a question answered about a particular tool or cluster resources?

  • Please contact the cluster team at cluster-help@luis.uni-hannover.de using the email address associated with your cluster account.
  • You can also call us on the phone +49 511 762 791000

However, please read this documentation first. If you find the documentation lacking something, let us know so we can update and improve it.

Whenever you have a question, please try to help us help you by providing the following information:

  • Do NOT simply reply to an old mail to create a new inquiry. Create a new one, choose a good subject. Otherwise, the topic will be both obsolete and completely different to what you really want. You will not get a timely response if we think you are just responding to an introductory course invitation.
  • State your username (nh…), Job ID(s) and locations on the system (directories, hostnames etc.)
  • NEVER send us your password. We do not need it. Sending your password will lead to your account being locked.
  • One problem per case: Nobody at the LUIS knows everything. If you pack several different topics into one case, fewer persons are able to answer them all, even if three out of your five questions would be easy to reply to. So the most difficult question in an inquiry will usually influence response time. One question at a time will usually get you answers much quicker. If things could depend on each other, then by all means describe them in one case, some things are complex.
  • Details known about the problem, e.g.
    • what command(s) in what sequence lead to the problem?
    • the time something happened; be precise if you can: log files are big and sometimes there are 1000 entries every minute
    • the batch script (as an attachment or - even better - its location on the cluster)
    • output from the program, if available, like myjob.o12345 and myjob.e12345 (as an attachment or - even better - its location on the cluster)
    • what is unusual or unexpected in the output files you already have?
    • what did you already try to solve the problem? Have you checked your quota (use the command checkquota)?
  • For questions related to file transfers or graphical logins: how do you access the cluster? Weblogin? PuTTY? X2Go? SSH? What is your workstation's OS?
  • Screenshots help, but consider doing copy&paste for plain text for textual information
  • After you got your response, do not just reuse the case to ask for something completely different. The person who to your first case may not know the answer to your new problem, but the case remains assigned to the same agent. One case per problem.

FAQ: Frequently asked questions

My jobs do not run - is there something wrong with the cluster?

→ try these two commands:

showq

squeue

If you see several of your jobs using showq, but none with squeue, or if you did submit your jobs using qsub instead of sbatch/salloc, you are trying to use the old PBS/Torque/Maui system, which has been gradually phased out over the past year (2021/2022). Since June 2022, the last useful resources have been migrated to Slurm, so now it's definitively time to migrate your jobs. It' usually a simple question of replacing your #PBS directives by their #SLURM counterparts.

The same goes for the Open OnDemand-portal; weblogin.cluster.uni-hannover.de points to the obsolete batch system, whereas login.cluster.uni-hannover.de directs you to the current scheduler, Slurm.


I can not connect to the cluster! OR Upload of file fails

→ First check whether you get any messages at all or if the system appears totally silent. If that is the case, check whether you are possibly “outside” of the LUH network. You'd then first need to connect via VPN.

→ If you can connect to the cluster from a shell (command line) via ssh, but are denied login graphically via X2Go, chances are high that you are over your quota (maximum disk space allocation) in the HOME directory and/or your grace period has expired. Use the command “checkquota” on the command line to verify this. Delete/Move files from within the ssh shell to get below your quota limits in HOME and then try again.


I get kicked out of my connection when trying to load a larger model or to compute something

→ you probably try to run something on the login nodes, which are unsuitable for computations and anything larger. Therefore, there is a limit of 1800 cpu seconds, after which processes get terminated. 1800 cpu seconds should be enough for months of shell access, but will get used up quickly when you try to calculate something on multiple cpu cores. Read the docs how the cluster is intended to be used. As a first start, check out our OOD-Portal on https://login.cluster.uni-hannover.de and submit an interactive job. It is never a good idea to try anything more than small tests, editing or a (small) compilation on a login node, since they are shared between all users (simply try the command w on the shell prompt to see how many others are working on the same machine).


The command checkquota tells me that I am over my quota, but where actually //are// these files?

→ use the command du -mad1 | sort -n in the file system that checkquota tells you it sees the problem. You can quickly change to the file system using the environment variables we automatically set for you, cd moves to your $HOME, cd $BIGWORK and cd $PROJECT to the other two major file systems.

Explanation: du = “check disk usage”, -m = “show megabyte units” (to enable numerical sorting afterwards), -a = “show all files, including those starting with a dot” (those are otherwise “hidden”, and some applications like e.g. Ansys use dot-directories e.g. for temporary files), -d1 = “only show files up to a depth of one (this level)” (otherwise the command would descend down the directory tree). | = pass the output of du to sort, which numerically (-n) sorts what it gets.


When trying to connect to the cluster, I get: "Missing font family helvetica, OpenGL might have problems on this machine"

→ You are probably using X2Go, and you did not check the “Full Installation” checkmark. Please reinstall X2Go and make sure all fonts are installed.


I get a message about the (external) email adress I use to get status mails about my jobs

→ Sending lots of very similar mail to external freemail providers leads to the uni-hannover.de Domain being blocked by those sites, which in turn leads to almost nobody external reveiving mail from LUH accounts or machines any more. Therefore, we ask you to use your institute's email account (the one ending in @xxxx.uni-hannover.de), and we also ask you to NOT setup an automatic forward to a Google, GMX or similar external freemailer account.


What is the meaning of "Script is written in DOS/Windows text format"?

guide/how_to_get_support.txt · Last modified: 2022/06/28 16:28