Add web post update for 2025

web/content/posts/2025-09-26/_index.md

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+---
+title: "Update 2025-09-26"
+author: "Rodrigo Arias Mallo"
+date: 2025-09-26
+---
+
+This is a summary of notable changes introduced in the last two years. We
+continue to maintain all machines updated to the last NixOS release (currently
+NixOS 25.05).
+
+### New compute node: fox
+
+We have a new [fox machine](/fox), with two AMD Genoa 9684X CPUs and two NVIDIA
+RTX4000 GPUs. During the last months we have been doing some tests and it seems
+that most of the components work well. We have configured CUDA to use the NVIDIA
+GPUs as well as AMD uProf to trace performance and energy counters from the
+CPUs.
+
+### Upgraded login node: apex
+
+We have upgraded the operating system on the login node to NixOS, which now runs
+Linux 6.15.6. During the upgrade, we have detected a problem with the RAID
+controller that caused a catastrophic failure that prevented the BIOS from
+starting.
+
+The `/` and `/home` partitions sit on a RAID 5 governed by a RAID hardware
+controller, however it was unable to boot properly before handling
+the control over to the BIOS. After a long debugging session, we detected that
+the flash memory that stores the firmware of the hardware controller was likely
+to be the issue, as
+[memory cells](https://en.wikipedia.org/wiki/Flash_memory#Principles_of_operation)
+may lose charge over time and can end up corrupting the content. So we flashed
+the latest firmware so the memory cells are charged again with the new bits and
+that fixed the problem. Hopefully we will be able to use it for some more years.
+
+The SLURM server has been moved to apex, so now you can allocate your jobs from
+there, including the new fox machine.
+
+### Translated machines to BSC building
+
+The server room had a temperature issue that affected our machines since the end
+of February of 2025. As the summer approached, the temperature exceeded the safe
+limits for our hardware, so we had to shutdown the cluster.
+
+![Room temperature](temp.png)
+
+Since then, we have moved the cluster to BSC premises, where now rests at a
+stable temperature, so hopefully we won't have more unscheduled downtime.