Rocky 9 benefits

The majority of the cluster has now been upgraded to Rocky 9 and the remaining CentOS 7 nodes will be updated in due course. There may be some users that are still hesitant to move over, but there are a few reasons why you should.

Security

CentOS 7 reached end of life (EOL) on 30th June 2024. Whilst we appreciate that some users may have required a grace period to finish off work that was in progress, continuing to use CentOS 7 is a security risk, and soon we will have to actively upgrade all remaining CentOS 7 nodes to remove this risk.

Improved performance

The applications installed centrally for all users and offered via Modules on Apocrita have all been re-compiled and re-installed. This has allowed us to install newer versions that bring new features and improved performance. The updated shared libraries and packages available on Rocky 9 have also allowed us to optimise compilation.

Let's take a popular application, plink. We offered both v1 and v2 on CentOS 7. Here are the jobstats for a simple benchmark run using 1 CPU core on CentOS 7:

-----------------------------------------------------------
|    NAME    |  DURATION | MEM R |  MEM U  | CORES |  EFF |
+------------+-----------+-------+---------+-------+------+
| plink1 C7  |   1:46:12 |   32G |  15.53G |     1 |  98% |
| plink2 C7  |   0:18:59 |   48G |  30.36G |     1 |  85% |
-----------------------------------------------------------

As we can see, v2 of plink already offers significant uplift in performance compared to v1. But what about on Rocky 9?

-----------------------------------------------------------
|    NAME    |  DURATION | MEM R |  MEM U  | CORES |  EFF |
+------------+-----------+-------+---------+-------+------+
| plink1 R9  |   0:42:01 |   32G |  15.39G |     1 |  92% |
| plink2 R9  |   0:12:50 |   48G |  25.83G |     1 |  79% |
-----------------------------------------------------------

Moving to plink on Rocky 9 would reduce the runtime of this job significantly. plink is just one of many applications where we have seen considerable uplift in performance since moving to a newer version on Rocky 9.

Improved support

We will no longer field support requests for jobs running on the few remaining CentOS 7 nodes, which are considered legacy and merely offered for users that need to complete existing workloads. We can only offer full support for troubleshooting, requests for new/alternative versions of centrally-installed applications etc. on Rocky 9.

Increased node availability

Since the majority of the nodes on Apocrita have now been upgraded to Rocky 9, continuing to use CentOS 7 means you are likely to queue for a long time for one of the few remaining nodes that are running CentOS 7.