Interactive Shell

Opening Interactive Shell Form

  • The first step is to select the Interactive apps and then click the Shell(Tmux) in the Open OnDemand dashboard.

  • Then you will see a form which needs to be filled to launch the interactive shell on compute nodes.

Shell Form

Partition

  • Partitions are work queues that has computational nodes in it to run the jobs. The partitions available in Discovery are cblab,cfdlab, iiplab, interactive, and normal.

  • However, you will see only the list of authorized partitions available for your Discovery account and hence, you won’t see the partitions which you don’t have authorization in the select dropdown.

  • Select one of the partitions where you want to submit your job. Refer to the page → Partitions in Discovery to select the ideal partition for your job.

  • By Default, partition is set to interactive.

  • Backfill partition is also enabled to launch MatLab GUI through the interactive session. However, jobs on Backfill are subject to being stopped and requeued. Hence, you need to fill the last form field with the MatLab command if you want to launch MatLab in Backfill.

For NMSU OnDemand interactive apps, Backfill partition is only available in MatLab (Xfce).

Walltime(Hours)

  • Sets the Walltime for your job. The job gets killed if the Walltime you set gets elapsed.

    Partition Max Hours

    backfill

    336

    cblab

    168

    cfdlab

    168

    iiplab

    168

    interactive

    24

    normal

    168

CPUs(Threads)

  • Sets the Number of CPUs(Threads) for the job. The below table shows the maximum limit for CPU threads for each partition. The default and minimum value is 1 CPU thread.

    Partition Max Limit

    backfill

    60

    cblab

    60

    cfdlab

    52

    iiplab

    52

    interactive

    16

    normal

    124

Memory (GB/Gigabytes)

  • Sets the memory for the job in terms of GB. The memory you select is available to all assigned threads for the job. The below table shows the maximum memory limit for each partition which can be requested for the job. The default and minimum value is 1 GB.

Partition Max Memory Limit(GB)

backfill

490

cblab

364

cfdlab

175

iiplab

175

interactive

64

normal

3000

GPUs

  • To enable the GPU selection, you need to choose one of the following partitions: cfdlab, iiplab, interactive, normal. Only these partitions have GPUs and if you select any of the partitions, you can see the GPUs dropdown enabled.

    Parameter #GPU

    Min Limit

    0

    Max Limit

    2

Node Selection

This is an optional node selection feature for submissions to Slurm. It allows users to specify a particular node or any node with specific feature flags.

Selection Options

There are four available options for node selection:

  1. Disabled: This is the default setting. When "Disabled" is selected, the application will not send any specific node preferences to Slurm during job submission.

  2. Node List: With this option, users can specify a particular node (one single node) where the job should run.

  3. Node Features (--constraint): Users can select this option if they want to run their job on any node that meets a specific feature.

  4. Node Features (--prefer): This option is similar to the "--constraint" option, but it only indicates a preference. If it’s not available, it might be scheduled elsewhere.

Email Address

  • If you want to get notified via email when the job starts/fails/ends, enter the email address associated with the Discovery account.

  • You can leave the text field blank if you don’t want job notifications.

Font Size

Set the font size for the terminal.

Parameter Font Size

Min Limit

10

Max Limit

30

Default

16

Terminal Multiplexer

You now have the flexibility to choose between Tmux and GNU Screen as your preferred Terminal Multiplexer.

By default, a pre-defined config file will be used. You can modify the default config file directly, or choose to use your own config file by put it in the specific path (see below).

  • If the corresponding config file doesn’t exist, it will be automatically generated the first time you run the Shell Interactive App.

  • Tmux - "/fs1/home/username/.config/tmux/tmux.conf" (recommended), or "/fs1/home/username/.tmux.conf"

  • GUN Screen - "/fs1/home/username/.screenrc"

Launching the Interactive Session

  • Once all the form fields are set, you can click the Launch button. The interactive session will be launched and you will see the below output.

Launch shell

  • The above output shows that the interactive Shell session has been launched successfully. You will see the Connect button only if the resources you have requested becomes available. Else, you might need to wait for some more minutes for the resources allocation and then the Connect button appears.

  • After it appears, click it.

The interactive session won’t be launched if you try to submit your job to the partition that you don’t have access to. You will get the following error message → Batch job submission failed: User’s group not permitted to use this partition. Also, the page gets reloaded and you need to select the value for the form fields again since the form gets reset.

Opening Shell

The Interactive Shell will be opened in a new tab.

Shell Output

You can close the tab and reconnect to the interactive shell again by using the Connect button from My Interactive Sessions tab again. This is because the session remains persistent as long as the time you have requested for the job didn’t get elapsed.

Killing the Interactive Session

To kill the interactive session after you are done, use the delete button from My Interactive Sessions tab.

Launch shell

A confirmation pop-up will appear and press Confirm to delete the session.

Whenever you are done with the work, it’s always recommended to kill/delete the interactive session running on the compute nodes and free the resources.