Frequently Asked Questions

Frequently Asked Questions – Access

Using the cluster is free of charge.

Neither for your user account nor for your project usage, you or your academic institution will be charged in any way.

However, operating and maintaining the HPC is quite an expensive business nonetheless (power consumption, cooling, administration). The compute resources should thus be used responsibly, by designing your compute jobs as efficient as possible.

User Account

While logged in on one of the login nodes, you can use the command account_expire to see your user account's end-of-validity date.

You will get an automatic email reminder 4 weeks before expiry of your account, and another one on the day of expiry.

To extend your account, simply fill and sign the “Nutzungsantrag” again, and send it to us fully signed via office post (or via your local contact person).

That can be caused by two basic reasons: the login node is not answering at all (perhaps due to being down or network problems), or it answers but denies you access.

  • Try another login node (the one you tried may be down)
  • In case of “Permission denied” (the login node answers, but denies you access), even from different login nodes: try changing your TUID password, as this is sync'ed to the HLR a few seconds later.
  • Read the (ssh) error message in its entirety. Sometimes it even explains how to fix the actual problem.
  • Try to log in explicitely with IPv4 or IPv6:
    ssh -XC –4 <tu-id@>lcluster15.hrz.tu-darmstadt.de
    ssh -XC –6 <tu-id@>lcluster17.hrz.tu-darmstadt.de
  • Already running the most recent version of your ssh/scp access program (PuTTY / KiTTY / BitVise / WinSCP / FileZilla)?
    From time to time, we refine the allowed (ie. considered safe) list of ssh key ciphers and negotiation algorithms, and some older program (versions) might be unable to work with these.
  • Have you made any recent changes in your login startup scripts .bashrc or .bash_profile? When failing, commands in these startup scripts can cause the bash to end prematurely, and that might look like you are denied access.
    If only interactive logins are affected, you can try accessing the likely culprit with your scp program (BitVise / WinSCP / FileZilla), and either
    • download it, comment the recent changes and re-upload it
      or
    • delete the troublemaker (and then restoring your last version from .snapshots/)

If nothing of the above works out: open a , always mentioning your TUID (no enrollment/matricle no) and preferably from your professional TUDa email address.

Avoid sending “screenshots” of your terminal window as pictures (jpg/png or the like). A simple copy&paste in text form of your login attempts and the resulting error message is sufficient.

If there isn't any explanatory error message, please use the “verbose” mode by running “ssh -vv …” and append the output to the ticket mail (again please not as screenshot/picture, but as text).

Projects

Your currently active projects / memberships are recorded daily in a file called .project in your HOME directory:

cat $HOME/.project

(see also “Hints” about project application).

  • Director of the institute: Most departments are organized into institutes (Fachgebiete). If this does not apply to your organization, please insert the dean, or a person with staff responsibility for the main research group.
  • PI: The principal investigator is responsible for the scientific aspects of the project. This can be the director as well as a junior professor, or post doc.
  • Main researcher/ Project manager: In general, this is the person who does the main part of work in this project. The PM is responsible for the administrative aspects of the scientific project. He or she is also the “technical contact” the HRZ communicates with.
  • Additional researchers: All other researchers who can compute on this project account. This includes other PhD students as well as students, who are working for the project.

The general project classes by amount of resources (Small, NHR-Normal and NHR-Large) are listed in our project class overview.

Beside plain computational projects, you might also be member of some rather technical billing accounts (eg. courses/trainings).

In general, we have the following naming pattern:

  • project<5#>
    This is a Small (or preparation) project
  • p<7#>
    This is a NHR project (regardless of whether -Normal or -Large)
  • special<5#>
    Technical projects for select groups
  • kurs<5#>
    Trainings, workshops and lectures with practical exercises on the Lichtenberg cluster (see Lectures and Workshops).

In general, one main researcher (PhD or post-doc) owns a project, ie. is project manager. This main researcher or PM can decide to add others to his or her project, for instance bachelor or master students, or a colleague he or she is collaborating with on this project.

All these coworkers need to have their own user account on the HLR before being added to a project.

Beware: while sharing your project account is explicitly allowed, sharing your user account is strictly prohibited!

In general, the Lichtenberg “local” or Small projects should be in the range and size of a PhD project, or to prepare NHR-Normal or -Large projects. For longer research terms and scientific endeavours, recurring follow-up projects are required.

Nonetheless, the initial proposal should outline the whole scientific goal, not only your 1st year's targets.

If the limit of a Small project is insufficient for your scientific challenge, apply for a NHR-Normal or NHR-Large project.

The project manager (PM or PoC – Person of Contact) is responsible for applying and (after completion) for reporting on the project.
He will be working with the HRZ for the (technical) reviews, and hand in the original of the signed proposal to the HRZ.

Students can apply for a bachelor or master thesis' project.

The proposal has to be signed by the PM and by the PI, who is required to be professor or post-doc.

For a “Small” (or preparation) project, only the web form needs to be completed, printed out, signed and sent to the HRZ.
This form mainly asks for technical details and a short abstract (150-300 words) of the scientific goals.

For the larger NHR projects, refer to the JARDS portal for details.

Small”/preparation projects can be submitted at any time and the proposals will be handled upon entry.

For the larger NHR projects, .deadlines (if any) can be found on the JARDS portal.

All projects are subjected to a technical review by the HRZ/HPC team.

If a project proposal is not sufficiently clear (ie. in terms of job sizes and runtimes), we wil contact the PM and ask for clarification or modification.

After the TR has been completed successfully, “Small” projects are started immediately.

NHR-Normal and NHR-Large projects are then scrutinized scientifically by (external) HPC experts from the field of the project..

Based on these reviews, the steering committee (Resource Allocation Board) approves (or denies) the proposal and assigns the resources, either as requested or in reduced form.

The maximum grant period for any given project is one year, regardless of the project's class.

If you know that your project needs less than a year, we suggest to write your proposal accordingly.
As the computational resources are allotted evenly over the granted time period, shorter projects get a greater resource share per month, resulting in higher priority per job.

In well-reasoned cases, a project can be extended beyond one year, for one or two months.

If your research project will take much longer than a year to complete, you will need to apply for follow-up projects every year.

Like you do it with your coworkers, referencing substantial contributions to your research publications should include the computational time grants from the Lichtenberg cluster. Properly communicating them improves public understanding of how research funds for HPC are spent and how we are working to support your research.

We thus kindly ask for an acknowledgment in all your publications arose out of or having used calculations on the Lichtenberg:

This work is funded by the Federal Ministry of Education and Research (BMBF) and the state of Hesse as part of the NHR Program.

If having been supported by the HKHLR, you could add:

This work is funded by the Federal Ministry of Education and Research (BMBF) and the state of Hesse as part of the NHR Program. The authors would like to thank the Hessian Competence Center for High Performance Computing--funded by the Hessen State Ministry of Higher Education, Research and The Arts--for helpful advice.

For all TU Biblio publications, the category „Hochleistungsrechner“ within the „Divisions” list (as a subcategory of „Hochschulrechenzentrum“) was added to TU Biblio.

Please use this category for your research publications related to the Lichtenberg Cluster, as then your publication will automatically be listed here accordingly.