statefulSet {. Like a Deployment, a StatefulSet manages Pods that are based on an identical container spec. Manages the deployment and scaling of a set of Pods, and provides guarantees about the ordering and uniqueness of these Pods. Here you can see how the Deployment itself runs a ReplicaSet that then runs 3 pods. So yes, StatefulSet helps preserve the order and name of the pod, but what is it that it does extra (or different) that is advantageous over a regular Deployment with respect to volumes. If there's heavy load, you can set up a HorizontalPodAutoscaler to. StatefulSets ensure stable network identities and ordered pod deployment/termination, which is crucial for maintaining data integrity. StatefulSets manage the deployment and scaling of a set of Pods, and provides guarantees about the ordering and uniqueness of these Pods. The resource may continue to run on the cluster indefinitely. The most basic difference is that you would get ability to persist pod level state with statefulsets. To create the MongoDB replica set, run these two commands: kubectl apply -f googlecloud\_ssd. As the Kubernetes manual states: StatefulSets are valuable for applications that require one or more of the following: Stable, unique network identifiers. To make it easier to eliminate fields or restructure resource representations, Kubernetes supports multiple API versions, each at a different API path, such as /api/v1 or /apis/extensions/v1beta1 and to extend the Kubernetes API, API groups is implemented. StatefulSets are used for deploying stateful applications that require stable network identities and persistent data. StatefulSet: Key Differences. StatefulSets are beneficial for apps that need: Steady and persistent storage. What is Kubernetes StatefulSets. Scaling a StatefulSet refers to increasing or decreasing the number of replicas. your state), so it cannot act as fast as Deployment (stateless) apps can. It makes sense for Operators to rely on them and benefit from the pod volume mapping handled by Kubernetes. It has to match the labels assigned to the pods. When using Kubernetes, most of the time you don’t care how your pods are scheduled, but sometimes you care that pods are. Statefulsets is used for Stateful applications, each replica of the pod will have its own state, and will be using its own Volume. Represents the latest available observations of a statefulset’s current state. 2. The labels are assigned in the “metadata” section in the deployment. Open this file in a code-editor and write the following code into it: apiVersion: apps/v1. StatefulSets Example Step 1 - Create Kube Environment. Just like StatefulSets, Kubernetes Deployments let you define the state of the application, and the Deployment’s controller is responsible for maintaining this state. This tool is tailored to provide developers with an experience of iteration…The containers in a pod talk to each other via local host, whereas pod-to-pod communication is done via services. Before you begin Before you begin this tutorial, you should familiarize yourself with the following Kubernetes concepts: Pods Cluster DNS Headless Services. 05, 2023 Image: Shutterstock / Built In Kubernetes is a powerful container orchestration tool that provides a variety of resources for managing. Kubernetes is an open-source platform that automates the deployment, scaling, and management of containerized applications. 27, this feature is now beta. In statefulsets each replica pod created has an index number starting from 0 and it will only setup the next replica if the previous one is running. What then is the advantage of using StatefulSets?Pic from k8s. What is Statefulsets? A StatefulSet is a controller that helps you deploy and scale groups of Kubernetes pods. 0 version. 6 StatefulSet vs Deployment: persistent storage; 8. In addition to managing the deployment and scaling of a set of Pods, StatefulSets provide guarantees about the ordering and uniqueness of those Pods. The following picture explains how scale down and scale up will happen in StatefulSets. The StatefulSet will not. To demonstrate just how pervasive the problem is, one can compare the list of charts using a StatefulSet vs a Deployment. Let’s understand both. It is similar to Deployment, but Statefulsets requires a Service Name . StatefulSet Kubernetes | Understand what StatefulSet in Kubernetes is and how it works Using StatefulSet in practice 🙅🏼♀️ youtu. DaemonSet Kubernetes has several ways to deploy applications, including deployments,. StatefulSet vs. StatefulSets and PDBs. Statefulsets only provide a way to have unique naming e. You can also create Pods (containers) using the Deployment object in the Kubernetes cluster. The domain managed by this Service. I want to deploy a single Pod on a Node to host my service (like GitLab for the example). Kubernetes StatefulSets are used to deploy stateful applications inside your cluster. StatefulSet. That's it! With these two commands, you have launched all the components required to run an highly available and redundant MongoDB replica set. Deployment Spec vs StatefulSet Spec Deployment specs and StatefulSet specs are quite similar. Deployment Strategy: There are two strategies available in the Kubernetes Deployment. StatefulSets. Statefulsets. In this documentation you will learn how HPA works, how to use it, what is supported etc. Identities are defined as: - Network: A single stable DNS and hostname. 3343 Perimeter Hill Drive. 2. StatefulSets . Deployment 适合场景无状态的应用特点1. Introduced in Kubernetes v1. This article is the fourth in a series using infrastructure as code to deploy applications with Kubernetes. Stable Network Identities: StatefulSets provide stable network identities for each pod, making it easy to communicate with specific pods in the set. Deployments configure apps in a generic way. StatefulSets Example. When you have an app which requires persistence, you should create a stateful set instead of deployment. g. StatefulSetではPodのSTATUSがUnknownになってもPodを自動起動しない。Kubernetes StatefulSets. Stable, persistent storage. As I mentioned in comments this can be done with help of StatefulSets. Deployments and StatefulSets are the most common way to scale workloads with KEDA. What is the difference between Deployment and StatefulSet components? 🤔 Deployment vs StatefulSet component Pods deployed by Deployment are identical and. Their purpose is to keep a set of identical pods running and upgrade them in a controlled way. When a StatefulSet's . Kubernetes Deployment vs. This is a simple example of the above one. Self-managed. 3. StatefulSets can be used to create pods with a guaranteed start-up order and unique identifiers. Stateful Applications in Kubernetes. Stateful and Stateless Applications. It allows you to define the Kubernetes Deployment or StatefulSet that you want KEDA to scale based on a scale trigger. yaml. #Deployment vs. Any application. 9. You can use DaemonSet to run a cluster storage, log collection, and node monitoring demon on each node. StatefulSets was introduced in Kubernetes 1. 部署、扩展、更新、删除都要有顺序…. In Kubernetes, StatefulSets are trying to solve the problem of your data going away when a Kubernetes Pod is destroyed. In the last lesson, we skipped over the whys and wherefores of StatefulSets to focus on implementing Secrets. When we scale down StatefulSets, the last pod gets deleted. A template describes a set of objects that can be parameterized and processed to…This task shows how to scale a StatefulSet. Statefulsets is used for Stateful applications, each replica of the pod will have its own state, and will be using its own Volume. headless service is necessary to create a stable DNS name for each pod. DaemonSet vs. Q6. To summarise, Kubernetes StatefulSet manages the deployment and scaling of a set of Pods, and provides guarantees about the ordering and uniqueness of these Pods. While the pods are all created based on. 3. Open this file in a code-editor and write the following code into it: apiVersion: apps/v1. You may need to delete the associated headless service separately after the StatefulSet. Currently we are using a Deployment and a ReplicaSet for this. You can deploy Elasticsearch master nodes as Kubernetes Deployments or StatefulSets. It is a simple application to start with since it does not require a complicated setup and it cannot be scaled. Other examples of stateful applications include MySQL clusters, Redis, Kafka, MongoDB, and others. Deploy it using the command below: $ kubectl apply -n test-namespace -f deployment. StatefulSets are meant to deploy applications that maintain their state. This blog post will discuss how this feature can be used. So yes, StatefulSet helps preserve the order and name of the pod, but what is it that it does extra (or different) that is advantageous over a regular Deployment with respect to volumes. statefulset "mariadb" deleted. They have different semantics while updating or when the pod becomes unreachable. There is a separate controller. Read stories about Statefulsets on Medium. kubectl create namespace database. K8s: Deployments vs StatefulSets vs DaemonSets. This binded volume is claiming ressources through the persistent volume claim. yaml file. Deployment vs. yaml with this way of working, it is easy to store the yaml-files in Git so you have full control of all changes and can revert/rollback. A DaemonSet ensures that a copy of a particular Pod is running on each node in a cluster or a subset of nodes, and it automatically adds or removes Pods from nodes as. Whereas, Deployment is more suited for stateful apps. It allows us to automate deployments, scale, and manage. 7) uses an update strategy to configure and disable. This appears to work : kubectl delete statefulsets mariadb -n openstack --force --grace-period=0 --cascade=false. This allows Pods to maintain individual state that's separate from their neighbors in the set. Each new pod in statefulset then have a new PV attached to them to. These are applications that can easily scale. Pods created by a StatefulSet have a unique and stable network identity. They function similarly to Deployments but assign a unique identifier to each Pod they encapsulate. 3343 Perimeter Hill Drive. Thus, you have one SQL Server instance deployed per pod in the Kubernetes cluster. Its just not worth the risk to see if your app supports concurrent writes, so dont guess. The Horizontal Pod Autoscaler is implemented as a Kubernetes API resource and a controller. . A StatefulSet is better suited to stateful workloads that require persistent storage on each cluster node, such as databases and other identity-sensitive workloads. Additionally, StatefulSets enables you to reschedule database pods to other nodes. These can be used to make sure that a pod. For example, look at web_stateful. The deployment uses a selector to match labels defined in the pod template. Their purpose is to keep a set of identical pods running and upgrade them in a controlled way. I will help you understand the use of Statefulsets, and also go through the differences between De. RollingUpdate: The RollingUpdate update strategy implements automated, rolling update for the Pods in a StatefulSet. This label ensures that child ReplicaSets of a Deployment do not overlap. Kubernetes Deployment vs. And kubectl rollout is used to check the above deployed application. These concepts are. Now let’s talk about StatefulSets. Their replicas are not identical as each one needs its own identity and storage. Cada una con sus características, ventajas y desventajas. Through StatefulSets, each Pod receives a stable, unique identifier, maintaining predictable and orderly deployment, which is indispensable for the. In Kubernetes, a Deployment is a workload resource object that lets you configure the lifecycle of pods in the cluster. Grafana Enterprise. Deployment is a resource to deploy a stateless application, if using a PVC, all replicas will be using the same Volume and none of it will have its own state. StatefulSets don’t create ReplicaSet so you cant roll back a StatefulSet to a previous version. ReplicaSets fall short when used to deploy a stateful application because they treat all the Pods the same, give them random hostnames and IP addresses that change on restarts. First of all Headless services are vaguely used to access all the pod replicas directly instead of using the Services. full vs. You can use StatefulSets to deploy stateful applications and clustered applications that save data to persistent storage, such as Compute Engine persistent. Deployment is best suited for stateless applications while StatefulSet is best suited for stateful applications. Not something I thought of a couple a years ago when the chart was made. But still for the alertmanager statefulset, only 1 pod is getting restarted. For hostnames, stable network identifiers please refer to the statefulset basics: For a StatefulSet with N replicas, each Pod in the StatefulSet will be assigned an integer ordinal, from 0 up through N-1, that is unique over the Set A StatefulSet can use a Headless Service to control the domain of its Pods. Identity and Stable Network hostnames: StatefulSets are used for those applications that require stable network identity and hostnames. Kubernetes Deployments vs StatefulSets (7 answers) Closed 2 years ago . 5, StatefulSets is an API object that manages the deployment and scaling of a set of Pods and provides guarantees about the ordering and uniqueness of these Pods. The list of stateful charts. To help deploy Pods, Kubernetes provides three different options: Deployments, DaemonSets, and StatefulSets. Overview. S tatefulSet represents a set of Pods with unique, persistent identities and stable hostnames. This can be extended to a scenario where different. It provides guarantees about the ordering and uniqueness of these Pods. StatefulSets are Kubernetes resources that allow us to deploy and manage the stateful application. Pods use a persistent volume claim as a request for storage that is matched to a persistent volume by the Kubernetes cluster. Why not to use the Statefulsets for stateless applications in Kubernetes ? As Stateful sets have the same capabilities as Deployment PVC, HPA, and others. Side note, you may consider deploying your SQL using Helm because someone else has already solved many of these issues using a chart so you don't have to. A. 申请转载. They guarantee stable and unique network identities, stable and persistent storage, and deployment and. DoK #49 Deployments vs. 4. StatefulSets is a new feature and, as a result, running this example will require an environment based on Kubernetes 1. The real distinctions of deployments vs statefulsets are: Ordering of pods. Using a statefulset also ensures that pods. $ export MYSQLPOD. 5 Post deployment tasks; 8. This is the expected behavior. yaml We need to create a pvc. –2. Kubernetes users don’t need to worry about how pods are scheduled—they can deploy pods sequentially, attach them to persistent storage volumes, and each pod maintains its own persistent network ID. You can see that with the kubectl get deploy and kubectl get statefulset> commands, both are ready. There is confusion amongst Kubernetes users as to when one should make a Deployment with a PVC and when they should use a StatefulSet with a PVC. Each instance is created one by one, and Kubernetes waits for each one to be up and running before proceeding to the next. StatefulSets are particularly useful when you have stateful applications, such as databases, that require stable network identities and persistent storage. - Storage: As many VolumeClaims as requested. It allows you to define the Kubernetes Deployment or StatefulSet that you want KEDA to scale based on a scale trigger. A StatefulSet is a set of pods with a unique, persistent hostname and ID. When you update the Pod template in a StatefulSet, the controller recreates the Pods with the updated template. StatefulSets: Use StatefulSets to deploy stateful applications. In the above YAML file, we have defined a simple StatefulSet to deploy a PostgreSQL database. Viewed 373 times. 9, so your version doesn't has support for it. 4 Creating a Service for the StatefulSet; 8. Remember that the default. According to kubernetes documentation about StatefulSets. To help deploy Pods, Kubernetes provides three different options: Deployments, DaemonSets, and StatefulSets. Using the Kubernetes Scheduler, the Deployment Controller runs replicas on any available node with available resources. StatefulSets is a new feature implemented in Kubernetes 1. Deploy The Stack. Deployment. For example, you define how many replicas ( pods) of your app you want to run in the. While StatefulSet is used for stateful applications, Deployment component is used to deploy stateless. Kubernetes Tutorial for Beginners. kubectl get pods NAME READY. StatefulSets in Kubernetes is a great feature to deploy and scale pods in Kubernetes. Since uptime-kuma is using SQLite, it only allows. Restarting a Rollout. On an update the existing Pods will get deleted and recreated. service "nginx" created. Similar to deployments, StatefulSets manage pods with identical container specifications. That's what happens with Pods when you create a Deployment, and it's a pattern which scales well. StatefulSets are used to scale-out stateful workloads since you define volumeClaimTemplates which allow the K8s Controller to replicate PVCs as you increase replicas. Comme un Déploiement, un StatefulSet gère des Pods qui sont basés sur une même spécification de conteneur. In Deployment, all pods are created parallelly. service都有ClusterIP,可以负载均衡 StatefulSet适合场景有状态的应用特点1. What it boils down to is that Deployment will create Pods with spec taken from the template. @Jarek the question was more whether you can technically use a normal service for a StatefulSet. 9) is a Kubernetes resource used to manage stateful applications. Remember that you can choose any namespace of your choice here. With just reads I can deploy Solr Cloud without any problems - using the SolrCloudClient in java. For mysql i am using statefulset and the code is here: apiVersion: apps/v1 kind:Author: Matthew Cary (Google) Kubernetes v1. It allows you to define the Kubernetes Deployment or StatefulSet that you want KEDA to scale based on a scale trigger. FYI: You had the right approach in the beginning with Deployment + PVC. Kubernetes StatefulSets provide two main advantages (for stateful applications) over Deployments: a stable identity of the pods and the ability to follow specific Deployment orders. The same thing can be done by using StatefulSets. upgrades/terminations are done sequentially from the pod with the biggest index number to the pod with index number 0. It dictates the needs of dedicated volumes, unique hostname records, and a specific order of deployment. StatefulSets handle the deployment and scaling of sets of Kubernetes pods, providing guarantees about their uniqueness and ordering. Reading Time: 4 minutes In Kubernetes we find different resources for deploying applications such as Deployment Statefulset daemonset In this blog, we will. Like. yaml. Ordered, graceful deletion and termination. However, Operators can go much further than what StatefulSets could possibly offer. Deployment is a resource to deploy a stateless application, if using a PVC, all replicas will be using the same Volume and none of it will have its own state. StatefulSet is also a Controller but unlike Deployments, it doesn’t create ReplicaSet rather itself. 4. 1 What is a StatefulSet? 8. Deployment is used to deploy stateless applications. MySQL, PostgreSQL, Redis, Elasticsearch) onto Kubernetes. Pods in a StatefulSet will have an IP. The StatefulSet controller uses this field as a collision avoidance mechanism when it needs to create the name for the newest ControllerRevision. The same thing can be done by using StatefulSets. Ordered, graceful deployment and scaling. Ordinals can start from arbitrary non-negative numbers. e. StatefulSets - A StatefulSet is similar to a deployment in that one or more identical pods are created and managed. Today, we’ll take a look at some of the same YAML markup, but zero in on StatefulSets instead. A Kubernetes pod is a cluster deployment unit that typically contains one or more containers. Kubernetes provides StatefulSets, a type of controller or workload used to deploy and run stateful applications in a Kubernetes environment. To check your version of Kubernetes, run kubectl version. 7 StatefulSet vs Deployment: associated serviceIt watches changes in ConfigMap and Secrets and then updates Deployment, StatefulSet and DaemonSet, so that the new changes are loaded. Unlike a. This sticky characteristic makes it possible to run databases on. They let you ensure that pods are scheduled in a specific order, that they have persistent storage volumes. StatefulSets are a Kubernetes resource specifically designed to manage stateful applications. There is a valid template in my answer, but you can't edit your deployment and modify it to statefulset. This allows you to easily replicate Pods and attach a storage volume to the Pods. StatefulSets and DaemonSets. The volumeClaimTemplates: will be used to create unique PVCs for each replica, and they have unique naming ending. 1 Answer. StatefulSets A StatefulSet is a workload API object for managing stateful applications. e. pod名字包含随机数字 4. Figure 3: Persistence in statefulsets as each having its own volume. 23 introduced a new, alpha-level policy for StatefulSets that controls the lifetime of PersistentVolumeClaims (PVCs) generated from the StatefulSet spec template for cases when they should be deleted automatically when the StatefulSet is deleted or pods in the StatefulSet are scaled down. If you update a StatefulSet, it also performs RollingUpdate i. No guarantee of unique network identities or persistent storage. Kubernetes Statefulsets are used to deploy Stateful Applications. 4. In Kubernetes, a Deployment is a workload resource object that lets you configure the lifecycle of pods in the cluster. A StatefulSet is a group of pods with persistent identities and stable hostnames, designed to run stateful and replicated Kubernetes services. Kubernetes StatefulSet simply explained | Deployment vs StatefulSet. As a result, running this example will require an environment based on Kubernetes 1. If you need to use deployment instead of statefulset, just add kind: Deployment to the nodeSpecs. 3343 Perimeter Hill Drive. It worked as expected and both the prometheus pods got restarted. What are some pros and cons of parallel podManagementPolicy over OrderedReady podManagementPolicy in StatefulSets? This totally depends on your application. The deployment uses a selector to match labels defined in the pod template. Deployments are usually used for stateless applications while StatefulSets are used for stateful applications. Headless Services: For stateful applications, use headless services to create stable network identities for each pod. The kubectl apply -f used to apply the configuration file kubernetes (where your deploy your desired application). This page describes the use of StatefulSet objects in Google Kubernetes Engine (GKE). Pods in StatefulSets have reliable network identities. As the name suggest the statefulsets are specifically used to make sure the app state is saved by each running pod. First sentence in the documentation: "The Horizontal Pod Autoscaler automatically scales the number of Pods in a replication controller, deployment, replica set or stateful set". Elaborate more on this if we should never use Deployment. We will take the example of Cassandra to learn about statefulset upgrade feature . First, let's verify that StatefulSet has created the leader ( mehdb-0) and. StatefulSets Example. When comparing a Deployment vs Replica Set, the former provides the same replication functions (through Replica Sets) and also the ability to rollout changes and roll them back if necessary. In this video, we cover Kubernetes Statefulsets in detail. Deployment is a resource to deploy a stateless application, if using a PVC, all replicas will be using the same Volume and none of it will have its own state. Kubernetes Deployment vs. These controllers can be used to group pods together according to their runtime needs and define pod replication and pod start up ordering. StatefulSet vs. There is also a general lack of understanding when it comes to disk access policies, what RWO/RWX means, and what they allow you to do. Let’s take a look at Deployments, DaemonSets, and StatefulSets. We can use the kubectl describe secret command to display additional information about the resource. Using the Kubernetes Scheduler, the Deployment Controller runs replicas on any available node with available resources. 8. com. Statefulsets is used for Stateful applications, each replica of the pod will have its own state, and will be using its own Volume. Each new pod in statefulset then have a new PV attached to. It’s easy to use and has a wide range of features, making it an ideal choice for managing applications in a production environment. They each have their own sticky identity, which they keep between. 9, you can autoscale your statefulsets using: apiVersion: autoscaling/v1 kind: HorizontalPodAutoscaler metadata: name: YOUR_HPA_NAME spec: maxReplicas: 3. In statefulsets each replica pod created has an index number starting from 0 and it will only setup the next replica if the previous one is running. You can also create Pods (containers) using the Deployment object in the Kubernetes cluster. Note: While ReplicaSets can be used, Kubernetes recommends using Deployments. ) What is Kubernetes StatefulSets? StatefulSet is a Kubernetes workload API object that can be used to manage stateful applications. They differ in terms of maintaining a persistent identity for each pod. It manages the deployment and scaling of a set of Pods, and provides guarantee about the ordering and uniqueness of these Pods. It manages the deployment and scaling of a set of pods, and provides a guarantee of ordering and uniqueness of the pods. 5 and becoming stable in 1. If you decide to use StatefulSets, note that it comes with a headless service per StatefulSet, generated for inter-cluster discovery. The solution(s) : Use a StatefulSet, ReplicaSet or DaemonSet to ensure the Pod creation after a Node failure. The manifest files do not have the namespace added to them. also during upgrades and deployments. Stateful applications are those which required persistent storage to work aptly. We recommend deploying one SQL Server container (instance) per pod in Kubernetes. 5 or later. Deployments mount a single persistent volume no matter the number of replicas: 10 pods of the same deploy will try to mount the same volume for both read and write operations. Parallel pod management tells the StatefulSet controller to launch or terminate all Pods in parallel, and not to wait for Pods to become Running and Ready or completely terminated prior to launching or terminating another Pod. If you want to provide workload persistence using Kubernetes persistent storage, you can incorporate a StatefulSet into your solution. You could set spec. Verify that the Pods are running using the kubectl get pods command. One of the more powerful features of a StatefulSet is the use of persistent. Users can deploy and maintain a set of highly available MySQL services in k8s based on StatefulSets, the process is relatively complex. Una aplicación stateless es aquella que no tiene estado, a la que no le importa la red en la que se esta. 2. Deployment is a resource to deploy a stateless application, if using a PVC, all replicas will be using the same Volume and none of it will have its own state. In the last lesson, we skipped over the whys and wherefores of StatefulSets to focus on implementing Secrets. This tutorial provides an introduction to managing applications with StatefulSets. So in total we wait 55 Minutes just to fill up the capacity. Pods hold the containers for an application. 喜欢. StatefulSetCondition describes the state of a statefulset at a certain point. Let's be friends: Explore managing stateful applications with Kubernetes StatefulSets — when to use them, how to deploy MongoDB. 安定したネットワーク識別子. Configuring the YAML for a DeploymentStatefulSet vs Deployment. Deployments allow you. StatefulSets. Just to avoid data corruption if you are changing the replica to more then one. As far as a Deployment is concerned, Pods are interchangeable. 0 or above. Roll back a deployment. Overall, StatefulSets are a valuable resource in Kubernetes that can help you manage stateful applications with confidence and predictability. @billimek it feels like a similar conversation happened on the original helm repo, so I'm not able to find it there. Statefulsets. StatefulSet represents a set of pods with consistent identities. StatefulSets and DaemonSets. Deploying a MongoDB Database: Here is an example of how to deploy a MongoDB database using a StatefulSet in Kubernetes. It manages the deployment and scaling of a set of Pods, and provides guarantee about. Kubernetes StatefulSet vs. They manage pods by assigning persistent identities for rescheduling and storage assignments, ensuring that pods always get the same unique ID and volume attachment when scheduled to another node. This tutorial demonstrates running Apache Zookeeper on Kubernetes using StatefulSets, PodDisruptionBudgets, and PodAntiAffinity. Statefulsets. What are StatefulSets and why are they needed? Deployments vs StatefulSets TL;DR. Eg. They keep unique identities for each Pod they manage and use the same identity when Pods need to be rescheduled. Un StatefulSet es el objeto de la API workload que se usa para gestionar aplicaciones con estado. This article contains best practices and guidance for running SQL Server containers on Kubernetes with StatefulSets. In summary, StatefulSets are great building blocks for running stateful workloads on Kubernetes. Once kubectl apply/create is performed, noticed that three persistent volumes are created dynamically. A pod is a single entity, and if it fails, it cannot restart itself; this won’t suit most use cases, as we want our. Thus providing reliably and some HA, even if there a single application instance running. We want to deploy service sets to machine "areas" so that services are running close to resources they manage. Why use StatefulSets. have the number of replicas in a text file (e. They are listed below. Step 1. It makes sense also as each Redis instance relies on a configuration file that keeps track of other cluster instances and their roles. Deployment vs. Their hostnames include their numerical replica identifier, allowing external applications to interact with the same replica after a Pod’s rescheduled. 所有pod共享存储 3. Case of statefulsets: name of pod initially: mongo-0 name of pod after it gets deleted & recreated: mongo-0 Here, pod name remained the same.