This incident was caused by resource contention in our orchestration layer. One of the components had a memory leak which resulted in a host using large amounts of swap which put additional stress on the other services run on the host. As a result, several hosts rebooted as they lost their connection to the orchestration layer. This incident affected one third of the EU-2 region hosts.
Fixes deployed during maintenance on Wednesday November 21st:
We are continuing to monitor the situation closely to ensure the issue does not present again.