Before we go all hands on into resizing StatefulSet Persistent Volumes, let’s do a brief recap into what are stateful applications, what a StatefulS

Resizing StatefulSet Persistent Volumes with zero downtime

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2021-06-22 06:00:06

Before we go all hands on into resizing StatefulSet Persistent Volumes, let’s do a brief recap into what are stateful applications, what a StatefulSet is, and how Kubernetes Storage works at a high level.

A stateless application is one that neither reads nor stores information about its state. By design, containers work best with stateless applications, as Kubernetes is able to create and remove containers in a rapid and dynamic manner.

A stateful application, on the other hand, saves data to persistent disk storage for use by the server, by clients, and by other applications. An example of a stateful application is a database or key-value store to which data is saved and retrieved by other applications.

StatefulSets are objects used to manage stateful applications. StatefulSets manage the deployment and scaling of a set of Pods, and provides guarantees about the ordering and uniqueness of these Pods.

The Kubernetes storage architecture is based in the abstraction of volumes. Volumes can be persistent or non-persistent, and Kubernetes allows containers to request storage resources dynamically, using a mechanism called volume claims.