What is the primary difference between Deployments and StatefulSets in Kubernetes?

What is the primary difference between Deployments and StatefulSets in Kubernetes?

• A. Deployments provide stable, unique identities for each pod
• B. StatefulSets provide a sticky identity for each pod
• C. Deployments guarantee persistent storage per pod
• D. StatefulSets are used for batch jobs only

Answer: (B)

Pod identity stability over time is what sets StatefulSets apart from Deployments. StatefulSets provide each pod with a stable, unique network identity that persists across rescheduling, typically exposed as a predictable hostname like my-app-0, my-app-1, and so on. They also offer per-pod storage that stays bound to the same pod ordinal, which is essential for stateful applications such as databases. Deployments, by contrast, manage stateless replicas; pods are interchangeable and their identities (names/IPs) aren’t guaranteed to be stable, so a particular instance cannot be relied on to keep its identity across restarts. Storage in Deployments isn’t tied to a specific pod in a durable way, whereas StatefulSets ensure a fixed identity and storage per pod. StatefulSets are used for stateful workloads, not batch jobs, which is why the notion of a persistent, sticky identity best describes the key difference.

Pod identity stability over time is what sets StatefulSets apart from Deployments. StatefulSets provide each pod with a stable, unique network identity that persists across rescheduling, typically exposed as a predictable hostname like my-app-0, my-app-1, and so on. They also offer per-pod storage that stays bound to the same pod ordinal, which is essential for stateful applications such as databases. Deployments, by contrast, manage stateless replicas; pods are interchangeable and their identities (names/IPs) aren’t guaranteed to be stable, so a particular instance cannot be relied on to keep its identity across restarts. Storage in Deployments isn’t tied to a specific pod in a durable way, whereas StatefulSets ensure a fixed identity and storage per pod. StatefulSets are used for stateful workloads, not batch jobs, which is why the notion of a persistent, sticky identity best describes the key difference.