Interactive jobs¶

The command “interactive” is recommended at NSC.

Usage: interactive -A [project_name] -t HHH:MM:SS

If you need more CPUs/GPUs, etc. you need to ask for that as well. The default which gives 1 CPU.

[x_birbr@tetralith3 ~]$ interactive -A naiss2025-22-403
salloc: Pending job allocation 44252533
salloc: job 44252533 queued and waiting for resources
salloc: job 44252533 has been allocated resources
salloc: Granted job allocation 44252533
salloc: Waiting for resource configuration
salloc: Nodes n340 are ready for job
[x_birbr@n340 ~]$ 

The command salloc (or OpenOnDemand through Gfx launcher) is recommended at PDC.

bbrydsoe@login1:~> salloc --time=00:10:00 -A naiss2025-22-403 -p main
salloc: Pending job allocation 9722449
salloc: job 9722449 queued and waiting for resources
salloc: job 9722449 has been allocated resources
salloc: Granted job allocation 9722449
salloc: Waiting for resource configuration
salloc: Nodes nid001134 are ready for job
bbrydsoe@login1:~>

Again, you are on the login node, and anything you want to run in the allocation must be preface with srun.

However, you have another option; you can ssh to the allocated compute node and then it will be true interactivity:

bbrydsoe@login1:~> ssh nid001134
bbrydsoe@nid001134:~

It is also possible to use OpenOnDemand through Gfx launcher.

To do this, login with ThinLinc and start the Gfxlauncher application. There is some documentation here: Interactive HPC at PDC.

Please be aware that the number of ThinLinc licenses are limited.

The command “srun” from command line works at C3Se. It is not recommended as when the login node is restarted the interactive job is also terminated.

[brydso@alvis2 ~]$ srun --account=NAISS2025-22-395 --gpus-per-node=T4:1 --time=01:00:00 --pty=/bin/bash
[brydso@alvis2-12 ~]$

The recommended way to do interactive jobs at Alvis is with OpenOnDemand.

You access the Open OnDemand service through https://alvis.c3se.chalmers.se.

NOTE that you need to connect from a network on SUNET.

More information about C3SE’s Open OnDemand service can be found here: https://www.c3se.chalmers.se/documentation/connecting/ondemand/.

The command salloc (or OpenOnDemand) is recommended at HPC2N.

Usage: salloc -A [project_name] -t HHH:MM:SS

You have to give project ID and walltime. If you need more CPUs (1 is default) or GPUs, you have to ask for that as well.

b-an01 [~]$ salloc -A hpc2n2025-151 -t 00:10:00
salloc: Pending job allocation 34624444
salloc: job 34624444 queued and waiting for resources
salloc: job 34624444 has been allocated resources
salloc: Granted job allocation 34624444
salloc: Nodes b-cn1403 are ready for job
b-an01 [~]$

WARNING! This is not true interactivity! Note that we are still on the login node!

In order to run anything in the allocation, you need to preface with srun like this:

b-an01 [~]$ srun /bin/hostname
b-cn1403.hpc2n.umu.se
b-an01 [~]$

Otherwise anything will run on the login node! Also, interactive sessions (for instance a program that asks for input) will not work correctly as that dialogoue happens on the compute node which you do not have real access to!

OpenOnDemand

This is the recommended way to do interactive jobs at HPC2N.

• Go to https://portal.hpc2n.umu.se/ and login.
• Documentation here: https://docs.hpc2n.umu.se/tutorials/connections/#open__ondemand

At UPPMAX, “interactive” is recommended.

Usage: interactive -A [project_name] -t HHH:MM:SS

If you need more CPUs/GPUs, etc. you need to ask for that as well. The default which gives 1 CPU.

[bbrydsoe@pelle1 ~]$ interactive -A uppmax2025-2-393 -t 00:15:00
This is a temporary version of interactive-script for Pelle
Most interactive-script functionality is removed
salloc: Pending job allocation 205612
salloc: job 205612 queued and waiting for resources
salloc: job 205612 has been allocated resources
salloc: Granted job allocation 205612
salloc: Waiting for resource configuration
salloc: Nodes p115 are ready for job
[bbrydsoe@p115 ~]$ 

salloc also works.

Usage: salloc -A [project_name] -t HHH:MM:SS

You have to give project ID and walltime. If you need more CPUs (1 is default) or GPUs, you have to ask for that as well.

[bbrydsoe@pelle1 ~]$ salloc -A uppmax2025-2-393 -t 00:15:00
salloc: Pending job allocation 205613
salloc: job 205613 queued and waiting for resources
salloc: job 205613 has been allocated resources
salloc: Granted job allocation 205613
salloc: Nodes p115 are ready for job
[bbrydsoe@p115 ~]$ 

The command interactive works at LUNARC. It is not the recommended way to do interactive work.

Usage: interactive -A [project_name] -t HHH:MM:SS

If you need more CPUs/GPUs, etc. you need to ask for that as well. The default which gives 1 CPU.

[bbrydsoe@cosmos2 ~]$ interactive -A lu2025-7-76 -t 00:15:00
Cluster name: COSMOS
Waiting for JOBID 1724396 to start

After a short wait, you get something like this:

[bbrydsoe@cn094 ~]$

GfxLauncher

This is the recommended wait to work interactively at LUNARC.

• Login with ThinLinc: https://lunarc-documentation.readthedocs.io/en/latest/getting_started/using_hpc_desktop/
• Follow the documentation for starting the GfxLauncher for OpenOnDemand: https://lunarc-documentation.readthedocs.io/en/latest/getting_started/gfxlauncher/