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FAQ

Overview

Access

How do I get access?
Do I need to pay money to use the cluster?
May I use your systems as part of an industry cooperation?
Does ZIMT have GPU nodes?
When will the new cluster be available?

Computations

Why do I have to create my own job scripts, can this not be automated?
I have an urgent deadline, can you increase my priority?
The jobs from user X run before mine, even though I queued my jobs first!
Can I reserve compute time?
Help, my job crashed!

Software

What software is installed on the cluster?
Could you install software X?
Could you update software Y?

Files

Help, I accidentally deleted files from my home directory!
Help, my workspace expired!

Access

How do I get access?

We explain the process here for employees and here for students. (Back to overview)

Do I need to pay money to use the cluster?

No, all employees and students of Uni Siegen may use the cluster without having to pay money. You might have to pay license fees to use specific software, for example Abaqus, in these cases you will be shown a warning when you load the module. (Back to overview)

May I use your systems as part of an industry cooperation?

No, unfortunately our systems may not be used for industry-financed projects. (Back to overview)

Does ZIMT have GPU nodes?

Yes, the OMNI cluster is equipped with 10 nodes with a total of 24 GPUs of type Tesla V100, more details here. (Back to overview)

When will the new cluster be available?

According to our current plans (as of mid-November 2020) the new cluster will be available by early December 2020. (Back to overview)

Computations

Why do I have to create my own job scripts, can this not be automated?

Even though the process of writing job scripts and queuing jobs might be simplified or automated further, we have decided not to do that in most cases. The main reason for this is that you are sharing the cluster with all other users and we want you to both develop some basic skills and be mindful of your resource use. (Back to overview)

I have an urgent deadline, can you increase my priority?

No. The capacity of the cluster is limited and the scheduler SLURM queues jobs according to a fair share/backfill algorithm which guarantees the shortest possible waiting time for all users. It is our stated policy not to interfere with this system. (Back to overview)

The jobs from user X run before mine, even though I queued my jobs first!

The prioritization algorithm used by SLURM has four main criteria:

  • Fair Share: when a user has used many resources (i.e. a lot of CPU time), the priority for the following jobs will decrease. This criterion is the most important one by far.
  • Age: the longer a job is waiting in the queue, the higher the priority
  • Job size: large jobs get a slight advantage to compensate the fact that they typically have to wait longer for an open slot of their size.
  • Backfilling: after the jobs have been sorted according to the above criteria, SLURM will fill the gaps with smaller jobs, meaning those will run earlier.

You can show job priorities with the sprio command. (Back to overview)

Can I reserve compute time?

Not for regular compute jobs. We may grant exceptions for specific lectures, so that the participants may run their jobs immediately during that lecture’s exercises. Please contact us if you are interested in that. (Back to overview)

Help, my job crashed!

This can have various reasons. First, you should search the SLURM logfile for error messages (especially near the end). If your job crashed with an error messages along the lines of “not enough memory”, that may be related to your SLURM settings, see also here.

If you cannot find the error, send the logfile and the job script, together with a description of the problem to hpc-support@uni-siegen.de. (Back to overview)

Software

What software is installed on the cluster?

On the pages in the Application Software category you can find an overview of the installed software and under Programming Languages there is a list of compilers and interpreters that are installed. If you already have cluster access you can show the installed modules with module avail (caution: some software may not be used by everyone at the university, or may require license fee, in those cases you will receive a warning message when loading the module). (Back to overview)

Could you install software X?

We decide what to install on a case-by-case basis. It is best if you come to our consultation hour or contact us by email. (Back to overview)

Could you update software Y?

We decide what to update on a case-by-case basis. To keep maintenance requirements manageable, and to ensure compatibility and security, we only install software from specific sources (for example the software repository of the operating system’s vendor) which may not always have the very latest version. (Back to overview)

Files

Help, I accidentally deleted files from my home directory!

There are daily automated backups being made of your home directory. If you do not wait too long (max. 30 days) you can restore your files yourself. We describe here how to do that. (Back to overview)

Help, my workspace expired!

In the first 10 days after your workspace expired you can restore it yourself. We describe here how to do that. (Back to overview)

Aktualisiert um 12:40 am 14. August 2018 von Jan Steiner