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On previous UI HPC systems it was possible to briefly ssh to any compute node, before getting booted from that node. This was sufficient to run an ssh command, for instance, on any node. This is not the case for Argon. SSH connections to compute nodes will only be allowed if you have a registered job on that host. Of course, qlogin sessions will allow you to login to a node directly as well. Again, if you have a job running on a node you can ssh to that node in order to check status, etc. You can find the node with the nodes-in-job command mentioned above. We ask that you not do anything except observe things while logged into the node as it may have shared jobs on it.
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While there are many software applications installed from RPM packages, many commonly used packages, and their dependencies, are built from source. See the Argon Software List to see view the packages and versions installed. Note that this list does not include all of the dependencies that are installed, which will be consist of newer versions than versions those installed via RPM. Use of these packages is facilitated through the use of environment modules, which will set up the appropriate environment for the application, including loading required dependenciesthe use of environment modules, which will set up the appropriate environment for the application, including loading required dependencies. Some packages like Perl, Ruby, R and Python are extendable. We build a set of extensions based on commonly used and requested extensions so loading modules for those will load all of the extensions, and dependencies needed for the core package as well as the extensions. The number of extensions installed, particularly for Python and R is too large to list here. You can use the standard tools of those packages to determine what extensions are installed.
Environment Modules
Like previous generation UI HPC systems, Argon uses environment modules for managing the shell environment needed by software packages. Argon uses LMod rather than the TCL modules used in previous generation UI HPC systems. More information about Lmod can be found in the Lmod: A New Environment Module System — Lmod 6.0 documentation. Briefly, Lmod provides improvements over TCL modules in some key ways. One is that Lmod will automatically load and/or swap dependent environment modules when higher level modules are changed in the environment. It can also temporarily deactivate modules if a suitable alternative is not found, and can reactivate those modules when the environment changes back. We are not using all of the features that Lmod is capable of so the modules behavior should be very close to previous systems but with a more robust way of handling dependencies. There is a module spider command that can be used to list modules. This is really designed for a hierarchical module layout, which Argon does not use, so there is little benefit to using module spider versus module avail to list the installed module files.
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Unix attributes were recently added to the campus Active Directory Service and Argon will be making use of those. One of those attributes is the default shell. This can be set via the following HawkID tool: Set Login Shell - Conch. Most people will want the shell set to /bin/bash. For reference, previous generation UI HPC systems set the shell to /bin/bash. We have observed that some people's shells are set to /bin/tcsh, which may not be what you want. We have no way of knowing whether those received the incorrect default or were changed via self-service. We recommend that you check your shell setting via the Set Login Shell - Conch tool and set it as desired before logging in. Note that changes to the shell setting may take up to 24 hours to become effective on Argon.
Queues and Policies
The University of Iowa (UI) queue
A significant portion of the HPC cluster systems at UI were funded centrally. These nodes are put into a queue named, 'UI'. There are also additional queues for special purposes.queues named UI or prefixed with UI-.
- UI → Default queue
- UI-HM→ High memory nodes
- UI-MPI → MPI jobs
- UI-GPU → Contains nodes with GPU accelerators
- UI-DEVELOP → Meant for small, short running job prototypes and debugging
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