[fedora-arm] ARM Build System Upgrading - Downtime Scheduled

[Chris Tyler]

At a Seneca team meeting this afternoon, we planned out the upgrade
process for the ARM build system.

There will be several pre-upgrade operations tomorrow and Monday, with
downtime scheduled to begin at 9 am EST / 1400 UTC on Tuesday, December
13. The upgrades should be completed within 48 hours (by 1400 UTC
Thursday, December 15). Builders will be disabled several hours before
the start of scheduled downtime to prevent new builds from starting.

The upgrades involve:

- Doubling the number of x86_64 servers, from two to four.

- Moving /mnt/koji to SSDs (supporting up to 117 KIOPS read and 69 KIOPS
write).

- Moving the Koji db to a separate server (using the SSDs we migrated to
yesterday).

- Switching to a 4-drive RAID-0 configuration for builder scratch space
(from a 2-drive JBOD).

- Physically re-racking and re-cabling the 60-70 machines for better
airflow and access.

- Adjusting backups, scripts, network configuration, and DNS to support
the new configuration.

--
Chris