Cloud-Native Microservices With Kubernetes - 2nd Edition

How Requests and Limits Affect Priority and Eviction

This is as simple as:

• Pods in the Guaranteed QoS class have the highest priority and are the last to be evicted when a node is under resource pressure.

• Pods in the Burstable QoS class have a medium priority and are evicted after BestEffort Pods but before Guaranteed Pods.

• Pods in the BestEffort QoS class have the lowest priority and are the first to be evicted when a node is under resource pressure.

This is like having three levels of seriousness when it comes to resource consumption.

• Guaranteed Pods know exactly what they need and get it, so they are the least likely to be evicted.

• Burstable Pods are not sure about their needs, but they estimate them, so they are in the middle of the eviction order.