rajeshpv · July 20, 2025 17:49 · Jul 20, 2025
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+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                   |
+
+---