In Kubernetes, Quality of Service (QoS) classes define how resources (CPU and memory) are allocated to pods, especially during times of resource contention. The three QoS classes are:

• Guaranteed
• Burstable
• BestEffort

Here’s a breakdown of the difference between Burstable and Guaranteed QoS classes:

---

✅ Guaranteed QoS

• Requirements:

  • Pod must have equal requests and limits for both CPU and memory for all containers.

• Behavior:

  • Kubernetes treats these pods with the highest priority.
  • Guaranteed resources are reserved for the pod.
  • Least likely to be evicted when a node runs out of memory.

• Use Case: Critical workloads that must not be interrupted, such as databases or key backend services.

---

⚡ Burstable QoS

• Requirements:

  • Pod has both requests and limits set, but they are not equal, or only set for some containers.

• Behavior:

  • Resources are guaranteed up to the request, but can burst up to the limit if resources are available.
  • Lower priority than Guaranteed but higher than BestEffort.
  • Can be evicted under memory pressure if higher priority pods need resources.

• Use Case: Non-critical apps that can scale up temporarily or tolerate being restarted.

---

Comparison Summary:

Feature	Guaranteed	Burstable
requests == limits	Yes (for all containers)	Not always (or partial containers)
Resource Priority	Highest	Medium
Eviction Risk	Lowest	Medium
Resource Usage	Reserved fully	Bursts above requests if resources are free
Ideal for	Critical apps	Apps with variable demand

---