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what is persistent volume in kubernetes

by Ova Cassin Published 3 years ago Updated 2 years ago
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Access Modes

Volume Plugin ReadOnlyMany ReadWriteMany
AWSElasticBlockStore - -
AzureFile
AzureDisk - -
CephFS
Jun 10 2022

A persistent volume is a piece of storage in a cluster that an administrator has provisioned. It is a resource in the cluster, just as a node is a cluster resource. A persistent volume is a volume plug-in that has a lifecycle independent of any individual pod that uses the persistent volume.

Full Answer

How to configure NFS based persistent volume in Kubernetes?

Configure NFS based PV (Persistent Volume) To create an NFS based persistent volume in K8s, create the yaml file on master node with the following contents, Run following kubectl command to verify the status of persistent volume. Above output confirms that PV has been created successfully and it is available.

Why is Kubernetes so popular?

Worker Nodes

  • Kubelet – Kubelet ensures that all containers in the node are running and are in a healthy state. ...
  • Kube Proxy – Acts as a network proxy and a load balancer. ...
  • Pods - A pod is the basic building block on Kubernetes. ...
  • Containers – Containers are the lowest level of microservice. ...

What does Kubernetes actually do and why use it?

These include the following:

  • Horizontal autoscaling. Kubernetes autoscalers automatically size a deployment’s number of Pods based on the usage of specified resources (within defined limits).
  • Rolling updates. Updates to a Kubernetes deployment are orchestrated in “rolling fashion,” across the deployment’s Pods. ...
  • Canary deployments. ...

Why does Kubernetes make use of a hypervisor?

  • Kubernetes orchestrating micro-VMs to provide stricter multi-tenant isolation for untrusted workloads.
  • Kubernetes orchestrating and managing traditional VM-based workloads (via KubeVirt) alongside container-based workloads.
  • Kubernetes clusters increasingly being deployed on bare metal servers, as an alternative to Kubernetes on VM-based environments.

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Why we use persistent volume in Kubernetes?

Persistent Volumes expose physical storage implementations to Kubernetes clusters so PODs can store and share data. With PVs, data generated and stored by immutable containers can be persisted for use throughout an application's lifecycle.

What is the difference between persistent volume and persistent volume claim?

PVCs are requests for those resources and also act as claim checks to the resource. So a persistent volume (PV) is the "physical" volume on the host machine that stores your persistent data. A persistent volume claim (PVC) is a request for the platform to create a PV for you, and you attach PVs to your pods via a PVC.

Why do we need volumes Kubernetes?

A Kubernetes volume is a directory that contains data accessible to containers in a given Pod in the orchestration and scheduling platform. Volumes provide a plug-in mechanism to connect ephemeral containers with persistent data stores elsewhere.

What is persistent storage volumes?

In containerization, persistent storage refers to storage volumes—usually associated with stateful applications such as databases—that remain available beyond the life of individual containers.

What is PV and PVC in Kubernetes?

PVs are volume plugins like Volumes, but have a lifecycle independent of any individual Pod that uses the PV. This API object captures the details of the implementation of the storage, be that NFS, iSCSI, or a cloud-provider-specific storage system. A PersistentVolumeClaim (PVC) is a request for storage by a user.

What is persistent volumes and why we use it?

A persistent volume is a piece of storage in a cluster that an administrator has provisioned. It is a resource in the cluster, just as a node is a cluster resource. A persistent volume is a volume plug-in that has a lifecycle independent of any individual pod that uses the persistent volume.

What are the types of Kubernetes volumes?

Types of Kubernetes VolumeemptyDir − It is a type of volume that is created when a Pod is first assigned to a Node. ... hostPath − This type of volume mounts a file or directory from the host node's filesystem into your pod.More items...

What is empty directory in Kubernetes?

emptyDir are volumes that get created empty when a Pod is created. While a Pod is running its emptyDir exists. If a container in a Pod crashes the emptyDir content is unaffected. Deleting a Pod deletes all its emptyDirs.

Where are Kubernetes volumes stored?

Depending on your environment, emptyDir volumes are stored on whatever medium that backs the node such as disk or SSD, or network storage. However, if you set the emptyDir. medium field to "Memory" , Kubernetes mounts a tmpfs (RAM-backed filesystem) for you instead.

What is persistent volume in Docker?

Volumes are the preferred way to persist data in Docker containers and services. Some use cases for volumes include: Sharing data among multiple running containers. If you don't explicitly create it, a volume is created the first time it is mounted into a container.

Why do we need persistent storage?

Persistence storage is necessary to be able to keep all our files and data for later use. For instance, a hard disk drive is a perfect example of persistent storage, as it allows us to permanently store a variety of data.

Why do containers need persistent storage?

Persistent storage retains data when a device is shut off. And for containers -- inherently stateless and ephemeral -- this type of storage is critical for deployments. Enterprises seeking resilient, scalable container deployments must get a handle on persistent storage.

What are Kubernetes persistent volumes?

In Kubernetes, the word PersistentVolume mention for storage of assets which can be designed to help us to control the storage of our applications, the assets of the persistent storage elements belong to the cluster and it goes independently to the pod, the persistent volume is the section of network storage that has been scaled by the administrator which has resources in the cluster that is independent of any separate pod which can use the persistent volume..

Kubernetes persistent volumes lifecycle

The lifecycle of the persistent volume has been started at provisioning, pass to the binding that is followed by using, and then it can transfer to reclaiming, retaining, and finally deletion. It has some steps in its lifecycle let us discuss as follows,

Kubernetes persistent types of volumes

The Kubernetes persistent types are executed as plugins in which some are given as follows,

Kubernetes persistent volumes – Use protection

In the production environment like database services it needs to access the highest available data storage, Kubernetes gives a lot of flexibility when it comes to persistent data storage in which every compound can use the particular mechanism for data storage.

Kubernetes persistent – Retained, Recycled, and Deleted

Retained: The ‘retain’ is a reclaim policy that allows for manual reclamation of the assets, when the persistent volume chain has been deleted then the PV quite exists.

Conclusion

In this article we conclude that the Kubernetes persistent volume is a segment of network storage that has been equipped by the administrator, we have also discussed the type of volumes, the lifecycle of Kubernetes persistent volume, and hence this article will help to understand the concept of persistent volumes in Kubernetes.

Recommended Articles

This is a guide to Kubernetes Persistent Volumes. Here we discuss the Kubernetes persistent volume is a segment of network storage that has been equipped by the administrator. You may also have a look at the following articles to learn more –

What is persistent volume?

In simple terms, the Persistent volume is a folder. The folder can be a local or cloud storage folder. The data created inside the Pod can be transferred to the persistent volume. The Persistent volume acts the same as like volume. However, the Persistent volume is an independent storage object. The Persistent volume is attached to the Pod using the Persistent volume claim.

How many access modes are there for persistent volume?

To access the persistent volume we had four different access modes. They are.

How much storage does a PVC pod have?

One PVC is created with the storage of 1GB. The status of PVC is pending. Once the PVC is attached to Pod then the status will be changed to bound.

What is volume in a pod?

In simple terms, volume is nothing but a folder in the worker node. The data created inside the Pod will be transferred to the worker node folder to avoid data loss using the volume concept when the Pod is deleted or restarted. Using the worker node folder is not recommended for a production application. So use third-party storage.

What does "no provisioner" mean?

kubernetes.io/no-provisioner => It means local storage. Change this value if you want to use other storage provisioner such as AWS, Azure or GCE etc.

Can a volume be read-write?

The volume can be mounted as a read-write by a single node. ReadWriteOnce access mode still can allow multiple pods to access the volume when the pods are running on the same node.

Does Kubernetes pod store data?

The Pod in the Kubernetes cluster does not store the data permanent ly in the Kubernetes cluster. To address this problem Kubernetes offers storage objects such as volume and persistent volume. The Persistent volume in the Kubernetes cluster offers a better storage solution. And the Persistent volume is an independent storage object. In this tutorial, you learned how to create a persistent volume and how to attach the persistent volume to the Pod.

What is a volume in Kubernetes?

In Kubernetes, a volume can be thought of as a directory which is accessible to the containers in a pod. We have different types of volumes in Kubernetes and the type defines how the volume is created and its content.

What is the advantage of Kubernetes volume?

A key advantage of Kubernetes volume is, it supports different kind of storage wherein the pod can use multiple of them at the same time.

What is NFS volume?

nfs − An nfs volume allows an existing NFS (Network File System) to be mounted into your pod. The data in an nfs volume is not erased when the Pod is removed from the node. The volume is only unmounted.

What is glusterfs volume?

glusterfs − Glusterfs is an open-source networked filesystem. A glusterfs volume allows a glusterfs volume to be mounted into your pod.

What is hostpath in pod?

hostPath − This type of volume mounts a file or directory from the host node’s filesystem into your pod.

What is persistent volume?

Persistent Volume (PV) − It’s a piece of network storage that has been provisioned by the administrator. It’s a resource in the cluster which is independent of any individual pod that uses the PV.

What is an emptydir?

emptyDir − It is a type of volume that is created when a Pod is first assigned to a Node. It remains active as long as the Pod is running on that node. The volume is initially empty and the containers in the pod can read and write the files in the emptyDir volume. Once the Pod is removed from the node, the data in the emptyDir is erased.

What is persistent volume?

A PersistentVolume (PV) is a storage resource in the cluster that has been provisioned by an administrator or dynamically provisioned using Storage Classes.

What happens if no static persistent volumes match the user's PVC request?

If none of the static persistent volumes match the user’s PVC request, the cluster may attempt to dynamically create a PV that matches the PVC request based on storage class.

What class determines what volume plugin is used for provisioning PVs?

Storage classes have a provisioner that determines what volume plugin is used for provisioning PVs.

What is default storage class?

If you set up a Kubernetes cluster on GCP, AWS, Azure, or any other cloud platform, a default StorageClass creates for you which uses the standard persistent disk type.

When none of the static PVs match a user’s persistentvolumeClaim, the cluster may try to?

When none of the static PVs match a user’s PersistentVolumeClaim, the cluster may try to dynamically provision a volume, especially for the PVC.

What is a volume claim template?

Volume claim templates are a list of claims that pods are allowed to reference. The StatefulSet controller is responsible for mapping network identities to claims in a way that maintains the identity of a pod.

Do you need a virtual disk to create a persistent volume?

Before creating a PersistentVolume, you must create a virtual disk in Azure.

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What Are Persistent Volumes?

  • Persistent volume (PV) is a piece of storage provided by an administrator in a Kubernetes cluster. When a developer needs persistent storage for an application in the cluster, they request that storage by creating a persistent volume claim (PVC) and then mounting the volume to a path in the pod. Once that is done, the pod claims any volume that mat...
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Persistent Volumes Use Cases

  • The common use cases for persistent volumes are providing storage for database applications and storage beyond the regular lifecycle of a pod.
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Understanding Persistent Volumes

  • Below is an example of a PersistentVolumeYAML file used for creating persistent volume storage: You can only create a PV resource declaratively. Kubernetes doesn’t provide an imperativeway of creating PV. Now, let’s look at the specifications of this YAML file.
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What Are Storageclasses?

  • StorageClass is used to define the storage classes offered in the Kubernetes cluster. It abstracts the underlying storage provider. For instance, you have an AWS Elastic Block Storage of 100Gi that you want to make available in the cluster. Think of StorageClassas the link that makes the Elastic Block Storage available in your cluster. However, you wouldn’t want applications in your c…
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Lifecycle of Persistent Volume and Persistent Volume Claim

  • Now that you have a deeper understanding of persistent volumes and persistent volume claims, we can look at the interaction between PVs and PVCs
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Bringing It Together

  • Let’s create a demo Nginx application bringing together all the concepts you have learned in this article. For this demo, you will be using MiniKubeto create a local Kubernetes cluster on your computer. Minikube also comes with a default StorageClass after installation, so you will be using that StorageClass for this demo. To check the StorageClass, run the command below: ‍ The Mini…
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Final Thoughts

  • Kubernetes persistent volumes provide storage for applications deployed in a Kubernetes cluster to store data for a very long time. This article introduced you to the concept of PV and its relationship to PVCs and StorageClasses. Furthermore, you learned about some PV use cases and how to create and configure PVs, PVCs, and StorageClasses. The summary of this piece is t…
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1.Videos of What Is Persistent Volume in Kubernetes

Url:/videos/search?q=what+is+persistent+volume+in+kubernetes&qpvt=what+is+persistent+volume+in+kubernetes&FORM=VDRE

11 hours ago 19 rows ·  · This document describes persistent volumes in Kubernetes. Familiarity with volumes is suggested. ...

2.Persistent Volumes - Kubernetes

Url:https://kubernetes.io/docs/concepts/storage/persistent-volumes/

4 hours ago A persistent volume is a piece of storage in a cluster that an administrator has provisioned. Learn more about Kubernetes persistent volumes containers, and virtual machines.

3.What Are Kubernetes Persistent Volumes? - NetApp

Url:https://www.netapp.com/devops-solutions/what-is-kubernetes-persistent-volumes/

20 hours ago  · The Kubernetes persistent volumes are defined as, it is a section of the repository in the cluster which has been equipped by an administrator by using the repository classes, it is …

4.Kubernetes Persistent Volumes | What are persistent …

Url:https://www.educba.com/kubernetes-persistent-volumes/

31 hours ago  · The Persistent volume in the Kubernetes cluster offers a better storage solution. And the Persistent volume is an independent storage object.

5.Kubernetes Persistent Volume Explained | by Bharathiraja …

Url:https://medium.com/codex/kubernetes-persistent-volume-explained-fb27df29c393

10 hours ago Persistent Volume and Persistent Volume Claim. Persistent Volume (PV) − It’s a piece of network storage that has been provisioned by the administrator. It’s a resource in the cluster which is …

6.Persistent Volume and Persistent Volume Claim

Url:https://www.tutorialspoint.com/kubernetes/kubernetes_volumes.htm

1 hours ago A Kubernetes persistent volume has the following attributes. It is provisioned either dynamically or by an administrator. What is persistent storage? Persistent storage is any data storage …

7.Persistent volumes (PV)and Claims (PVC) in Kubernetes

Url:https://medium.com/avmconsulting-blog/persistent-volumes-pv-and-claims-pvc-in-kubernetes-bd76923a61f6

21 hours ago  · A persistent volume claim (PVC) is a request for storage by a user from a PV. Claims can request specific size and access modes (e.g: they can be mounted once read/write …

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