Burstable QoS is assigned to Pods that do not meet the criteria for Guaranteed QoS but have at least one container with memory or CPU requests defined.

Pods with the Burstable QoS are guaranteed minimal (requested) memory usage. They might be able to use more resources if they are available. If the system is under pressure and needs more available memory, containers belonging to the Pods with the Burstable QoS are more likely to be killed than those with Guaranteed QoS when there are no Pods with the BestEffort QoS. You can consider the Pods with this QoS as medium priority.

Finally, we reach the last QoS class.