Nexus/ClusterOSUpgrade

Overview

UMIACS Technical Staff has begun the process of upgrading the operating system version on all Nexus cluster nodes from Red Hat Enterprise Linux (RHEL) 8 to 9 as of 9am on Monday 06/01/2026.

RHEL8 is in the Maintenance Support phase of its life cycle and is transitioning to the Extended Life phase in 2029. More information on Red Hat's lifecycle policy for its operating systems can be found here. We are staying well ahead of the Extended Life phase date for our cluster nodes by performing these upgrades now.

RHEL9 is still in the Full Support phase of its life cycle and introduces a newer major Linux kernel version and newer glibc version, improving compatibility with many newer software applications.

Scheduling

Upgrades for all cluster nodes have begun. We expect to be finished with all cluster node upgrades no later than 5pm on Friday 08/21/2026.

Submission Nodes

Submission nodes with the number '01' in their hostnames have been upgraded as of 06/01/2026.

Submission nodes with the number '00' in their hostnames, if not already upgraded, will be scheduled for upgrade individually in the near future. Staff will send a notification to individual lab's/center's cluster users to schedule the relevant '00' node's upgrade when ready. The actual date of each upgrade will be no less than one week after the corresponding notification has been sent.

Data in UNIX filesystem storage spaces on each submission node, i.e., /tmp and /scratch0, will not be preserved during upgrade. If you have any data in any such space on the '00' submission node in a pairing that you want to keep, please ensure you copy it to the '01' submission node or a network-attached filesystem storage space prior to the '00' node's upgrade date. Data in network-attached filesystem storage spaces, such as /nfshomes or /fs/nexus-scratch, will not be affected.

Compute Nodes

All compute nodes have been upgraded as of 07/24/2026.

Interoperability

Software and Modules

Please transition your virtual environments, workflows, etc. to work with RHEL9 as soon as possible. You can use the '01' submission node that you have access to for transitioning and light testing - as always, please do not run any computationally intensive processes on this node. It is intended to be a host for configuring environments/workflows and submitting jobs only. If you need to do more involved testing, please schedule a job for this.

The module tree for RHEL9 is populated with a large number of the same modules that are available in the RHEL8 module tree, although specific modules may have different versions available in the RHEL9 tree as compared to the RHEL8 tree. If you have a dependency on a specific version of a module that is not available in the RHEL9 tree, please contact staff and we can get one created.