ARC System Changes: 2025-01

During the week of January 6-10, ARC systems were offline for maintenance. During this time several major changes were implemented. This page presents a brief outline of the changes that were made, explains the impact it may have on your use of ARC systems, and provides a FAQ regarding these changes.

Outline of Changes

Tinkercliffs Operating System Upgrade from CentOS 7 to Rocky 9

The base operating system (OS) on Tinkercliffs login and computed nodes had remained static since the cluster was first deployed in 2020. CentOS 7 was used as the OS but reached its end of life and end of updates in 2024. The cluster clearly still has value as a computational resource, but to keep it operational, it must run a supportable OS. The CentOS series of RedHat clone Linux distributions was terminated in the early 2020’s and ARC, like many other research computing centers, tested and decided on the Rocky Linux platform as a replacement for CentOS.

All the login and compute nodes in the cluster except for the 10 DGX GPU nodes were reprovisioned with Rocky 9. Some initial tests of the installed software stack were unfavorable and ARC decided that it should be rebuilt from the ground up for the new OS.

New Open OnDemand

An updated version of Open OnDemand was deployed to replace and update our existing installation. Along with this, we are overhauling the “Interactive Apps” provided through Open OnDemand. Newer apps will run with newer software versions and will have improved features, performance, and stability.

Some notes from the January 8th release of the new Open OnDemand instance:

  • New applications for JupyterLab/MATLAB, currently Owl only, other clusters will be added soon

  • New Desktop App

    • User home is now mounted under /home/$USER/clusterhome, projects is still at /projects

    • Firefox updated, homepage now set to the ARC docs site

    • SSH-less X forwarding, Just open the terminal under the “other” category in the xfce applications menu and run GUI apps from the node.

    • Image viewer (ristretto) and movie player (mpv) also installed

  • Previous “Interactive Apps” moved to “Legacy Apps” dropdown

  • Pinned apps removed, same apps are available in the dropdowns.

  • Jobs Composer link removed from the UI, though it is still accessible

/scratch and /common replacing /globalscratch and /global

ARC has several current initiatives including an effort to provide uniform and consistent computing platforms and settings. This means we’re heading towards a single, common OS on all clusters, consistent software availability on all clusters, and consistent storage mount points.

Upon release from maintenance, all clusters will have scratch storage mounted at /scratch and common, public datasets at /common. This supersedes the current filesystems mounted at /globalscratch and /global respectively.

Data currently on these filesystems is unchanged. To avoid breaking existing job scripts, we have provided symlinks so that the old mount points will continue to work,

previous

new

/globalscratch/<username>

/scratch/<username>

/global

/common

Please adjust your scripts to use these new names at your earliest convenience.

/fastscratch and /vtarchive removed from clusters

Following lengthy waits after repeated notifications, these two older filesystems have been removed from all ARC clusters. The hardware which runs them is end-of-life.

ARC will work directly with people who had data on /vtarchive to determine a suitable destination for the data.

ARC will accept requests for recovery of data from /fastscratch for a limited period of time, but generally consider data here to be abandoned scratch data which can be deleted.

If you have questions about this, please submit a help request via https://arc.vt.edu/help.

Answers for some frequently asked questions (FAQ)

“The software module I used before maintenance isn’t there now. Can you reinstall it for me?”

Yes, we preinstalled as many packages as we could and software installations are getting priority attention for the weeks after the Tinkercliffs cluster was reprovisioned. Additionally, ARC is making a concerted effort to standardize the software available across all clusters.

Use module spider <string> from the command line to search for packages which are already installed on Tinkercliffs nodes. If a package you need is not found, please submit a help request via https://arc.vt.edu/help. We will add it to our to-do list.

“What does ‘Legacy Apps’ on Open OnDemand mean?”

Before the maintenance, our Open OnDemand (OOD) apps were developed for the Tinkercliffs cluster with containerized implementations. Due to the containerization, much of the apps functionality remains in tact after the update to the operating system. Therefore, we are keeping them available as we continue to develop OOD. While we have tested the more commonly used ones like RStudio, Matlab, and Desktop, be advised that there may be some issues with Legacy apps since they were developed for the previous system.

We are actively developing new and improved apps. You can see the recently release apps in the “Interactive Apps” dropdown as before.

“How can I recover data from /fastscratch?”

Since there are already a few users who need to access data from the old filesystem, we decided to proceed with syncing the entire source. It’s about 300TB and 120 million files, so we expect this transfer to be complete in couple weeks. Please submit a help request (https://arc.vt.edu/help) so that we can let you know when the data is available for you to retrieve it.