concept qos class in category kubernetes

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Figure 14.4. Resource requests, limits and QoS classes

Thinking about what QoS class a pod has can make your head spin, because it involves multiple containers, multiple resources, and all the possible relationships between requests and limits. It’s easier if you start by thinking about QoS at the container level (although QoS classes are a property of pods, not containers) and then derive the pod’s QoS class from the QoS classes of containers.

Figuring out the QoS class of a pod with multiple containers

For multi-container pods, if all the containers have the same QoS class, that’s also the pod’s QoS class. If at least one container has a different class, the pod’s QoS class is Burstable, regardless of what the container classes are. Table 14.2 shows how a two-container pod’s QoS class relates to the classes of its two containers. You can easily extend this to pods with more than two containers.