Kubernetes ephemeral storage drivers#
Kubernetes ephemeral storage series#

These concepts have been covered extensively in the DCA exam preparation tutorial series, so any candidate confident with the topic can skim through this part. The following chapters are dedicated to giving the candidate a complete understanding of storage concepts in Docker.

Kubernetes ephemeral storage drivers#

Docker storage encompasses two major concepts, storage drivers and volume drivers.

Kubernetes ephemeral storage series#

This section of the tutorial series dives deep into how storage is handled in containers as this lays the foundation for how Kubernetes provisions and manages volumes to provide storage for containerized applications. Storage in Docker IntroductionД«efore exploring storage in Kubernetes, it is important to understand storage in containers. With a grasp of these concepts, the candidate can provision storage for Kubernetes applications, whether locally, or through other supported volumes such as AWS ElasticBlockStore, azureDisk, cephfs, cinder, etc. This section only explores the resources and concepts available within Kubernetes. Kubernetes supports many Volume Types and storage options from a wide range of cloud service providers. This section delves into Volumes, PVs, PVCs and Storage Classes that help to manage the consumption of storage resources in Kubernetes clusters. With Volumes, it is easy to manage the sharing of files between containers in a Pod and recover files in case of a container crash. A Volume is a storage object that retains and avails data to containers running in a POD. Kubernetes provides Persistent Volume (PV), Persistent Volume Claim (PVC) and Storage Class APIs so that administrators can abstract the consumption of storage from its provision. The ephemeral nature of containers presents challenges when it comes to managing storage for Kubernetes compute instances.

13 min read Introduction to Kubernetes Storage.

If there is a PersistentVolume (PV) that satisfies the specified requirements in the PersistentVolumeClaim (PVC), it will be bound to the PVC before the Pod starts. For example, a Pod may need a volume that is at least 4Gi large or a volume mounted under /data in the containerвЂ™s filesystem. A PersistentVolumeClaim can request specific size and Access Modes (for example, they can be mounted once read/write or many times read-only).ДЄny workload can specify a PersistentVolumeClaim. For a workload that requires persistent volumes, the workload should use PersistentVolumeClaim (PVC) to express its request on persistent storage. Persistent Volume ClaimДЄ PersistentVolumeClaim is a request for storage. In order to use a Persistent Volume (PV), your application needs to invoke a Persistent Volume Claim (PVC). The Persistent Volume API objects capture the details of the implementation of the storage, be that NFS, iSCSI, or a cloud-provider-specific storage system. Unlike ephemeral storage, the lifecycle of a PersistentVolume is independent of that of the workload that uses it. Persistent Volumes are resources that represent storage in the cluster that has been provisioned by an administrator or dynamically provisioned using Storage Classes. For those cases, the workloads need to use PersistentVolumes (PV). For instance, a database server needs to recover database files after it crashes.

You may have stateful workloads requiring persistent storage whose lifecycle is longer than that of Pods or containers. Persistent Volumes are volume plug-ins that have lifecycle capabilities that are independent of any Kubernetes Pod or Deployment. Persistent Volumes are storage resources that can be used by the cluster.

You may need to express the capacity requests for ephemeral storage so that kubelet can use that information to make sure it does not run out of ephemeral storage space on each node. Managed by container runtime (e.g., under /var/lib/containerd).Д®phemeral storage is automatically managed by Kubernetes, and typically does not require explicit settings.

Managed by kubelet under /var/lib/kubelet. For example, the following are examples of ephemeral storage provided by Kubernetes: EmptyDir volume. This document describes the model used in Kubernetes for managing persistent, cluster-scoped storage for workloads requiring access to persistent data.ДЄ workload on Kubernetes typically requires two types of storage:Д®phemeral storage, by its name, is ephemeral in the sense that it is cleaned up when the workload is deleted or the container crashes.