Impaired Instances

When an instance is marked as impaired, it means that something is wrong with the instance, eg. the underlying physical hardware was faulty or faulty network equipment cut off its network.

All data is always safe as long as you have persistent messages and durable queues:  https://www.cloudamqp.com/blog/2017-12-29-part1-rabbitmq-best-practice.html

That something is impaired is not anything we or you can prevent, it's all in the hands of the datacenter. It happens but it's rare. However, a 2-node setup will keep your other node up and running when the first node needs to be replaced.