Capacity, availability and staying up under load.
4 items at advanced level · all topics
A company runs a business-critical application in one AWS Region. The disaster recovery plan requires a recovery time objective of 10 minutes and a recovery point objective of 1 minute in a second Region. The company wants to avoid paying for a full duplicate of the production fleet. Which disaster recovery strategy should a solutions architect choose?
RTO and RPO in minutes rule out backup and restore and pilot light, because both require standing infrastructure up before traffic can move. Warm standby keeps a scaled-down copy always running, which is what buys minutes instead of hours without paying for a second full fleet.
A cluster must be rolled back to an etcd snapshot taken this morning. The control plane is still running. What does the documented restore procedure require?
Stop every API server first, restore the snapshot into a fresh data directory, then start the API servers again. Restoring under a live API server is explicitly warned against.
A team is planning a highly available control plane and must choose between the stacked etcd topology and the external etcd topology. Which statement correctly describes the trade-off?
Stacked etcd runs an etcd member on each control plane node, so losing a node loses both an API server and an etcd member. External etcd separates the two at the cost of twice the hosts.
kubectl drain is taking a node out of service and appears to hang, evicting nothing further. A PodDisruptionBudget on the affected app sets minAvailable: 3 and exactly 3 Pods are ready. What is happening?
drain uses the Eviction API, which respects PodDisruptionBudgets. With minAvailable already at the limit, no further eviction is allowed until a replacement Pod becomes ready somewhere else.