Add docs for autoscaler bug
# Frequently Asked Questions
+## On AWS, why do user instances occasionally die ~30 minutes after spinning up a large dask cluster?
+
+AWS uses Amazon's Elastic Kubernetes Service (EKS) for hosting the
+kubernetes cluster. [EKS requires the use of at least two availability
+zones](https://docs.aws.amazon.com/eks/latest/userguide/network_reqs.html_). The
+QHub cluster has an
+[autoscaler](https://docs.aws.amazon.com/eks/latest/userguide/cluster-autoscaler.html)
+that has a default service that automatically balances the number of
+EC2 instances between the two availabilty zones. When larger dask
+clusters are created and destroyed, occasionally the autoscaler will
+attempt to reschedule a user pod in the other availability zone. When
+this happens, Kuberenetes doesn't sucessfully transfer the active pod
+to the other zone and the pod dies.
+
+To stop this occuring, the autoscaler service "AZRebalance" needs to
+be manually suspended. Currently this autoscaler service is not managed
+by terraform. Disabling it via the console will be permanent for the
+life of the cluster. [There is an open issue to permantly fix this via
+terraform](https://github.com/Quansight/qhub/issues/786)
+
+To disable the AZRebalance service, follow the steps in this [AWS
+documentation](https://docs.aws.amazon.com/autoscaling/ec2/userguide/as-suspend-resume-processes.html)
+to suspend the AZRebalance service.
