Kubernetes PVC共享一个PV? [英] kubernetes PVCs sharing a single PV?

问题描述

我正在尝试为3个Pod部署一个持久卷来工作，我想使用集群的节点存储，即不像ebs那样剥离外部存储.

I am trying to deploy a persistentvolume for 3 pods to work on and i want to use the cluster's node storage i.e. not an external storage like ebs spin off.

为达到上述目的，我做了以下实验-

To achieve the above i did the following experiment's -

1)我仅应用了下面定义的以下PVC资源-

1) I applied only the below PVC resource defined below -

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  creationTimestamp: null
  labels:
    io.kompose.service: pv1
  name: pv1
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
status: {}

此旋转是默认情况下的存储集storageclass，在我的情况下，它是数字海洋的容量.因此，它创建了一个1Gi的卷.

This spin's up a storage set by default storageclass, which in my case was digital ocean's volume. So it created a 1Gi volume.

2)如下创建了PV资源和PVC资源-

2) Created a PV resource and PVC resource like below -

apiVersion: v1
kind: PersistentVolume
metadata:
  name: task-pv-volume
  labels:
    type: local
spec:
  storageClassName: manual
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: "/mnt/data"

---

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  creationTimestamp: null
  labels:
    io.kompose.service: pv1
  name: pv1
spec:
  storageClassName: manual
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
status: {}

发布此帖子后，我看到我的主张受到约束.

Post this i see my claim is bound.

    pavan@p1:~$ kubectl get pvc
    NAME        STATUS   VOLUME           CAPACITY   ACCESS MODES   STORAGECLASS   AGE
    pv1   Bound    task-pv-volume   10Gi       RWO            manual         2m5s
    pavan@p1:~$ kubectl get pv
    NAME             CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM               STORAGECLASS   REASON   AGE
    task-pv-volume   10Gi       RWO            Retain           Bound    default/pv1   manual                  118m
pavan@p1:~$ kubectl describe pvc
Name:          pv1
Namespace:     default
StorageClass:  manual
Status:        Bound
Volume:        task-pv-volume
Labels:        io.kompose.service=pv1
Annotations:   kubectl.kubernetes.io/last-applied-configuration:
                 {"apiVersion":"v1","kind":"PersistentVolumeClaim","metadata":{"annotations":{},"creationTimestamp":null,"labels":{"io.kompose.service":"mo...
               pv.kubernetes.io/bind-completed: yes
               pv.kubernetes.io/bound-by-controller: yes
Finalizers:    [kubernetes.io/pvc-protection]
Capacity:      10Gi
Access Modes:  RWO
VolumeMode:    Filesystem
Mounted By:    <none>
Events:
  Type     Reason              Age                 From                         Message
  ----     ------              ----                ----                         -------
  Warning  ProvisioningFailed  28s (x8 over 2m2s)  persistentvolume-controller  storageclass.storage.k8s.io "manual" not found

以下是我希望得到的答案/指标-

Below are my questions that i am hoping to get answers/pointers to -

1. 以上警告，找不到存储类，我需要 创建一个?如果是这样，您能告诉我原因和方式吗?或任何指针. (以某种方式，该链接未声明- https: //kubernetes.io/docs/tasks/run-application/run-single-instance-stateful-application/)

1. The above warning, storage class could not be found, do i need to create one? If so, can you tell me why and how? or any pointer. (Somehow this link misses to state that - https://kubernetes.io/docs/tasks/run-application/run-single-instance-stateful-application/)

请注意，PV的存储容量为10Gi，PVC的请求容量为1Gi，但是PVC仍然具有10Gi的容量吗?我不能与其他PVC共享相同的PV容量吗?

Notice the PV has storage capacity of 10Gi and PVC with request capacity of 1Gi, but still PVC was bound with 10Gi capacity? Can't i share the same PV capacity with other PVCs?

对于问题2)如果我必须为具有所需容量的不同PVC创建不同的PV，我是否还需要创建storageclass?还是相同的存储类别，并使用选择器选择相应的PV?

For question 2) If i have to create different PVs for different PVC with the required capacity, do i have to create storageclass as-well? Or same storage class and use selectors to select corresponding PV?

推荐答案

我试图重现所有行为以回答您的所有问题.但是，我无权访问DigitalOcean，所以我在GKE上对其进行了测试.

I was trying to reproduce all behavior to answer all your questions. However, I don't have access to DigitalOcean, so I tested it on GKE.

找不到以上警告，存储类，我是否需要 创建一个?

The above warning, storage class could not be found, do i need to create one?

根据文档和最佳实践，强烈建议创建一个storageclass，然后再基于它创建PV/PVC.但是，有一种称为手动配置"的东西.您在这种情况下所做的.

According to the documentation and best practices, it is highly recommended to create a storageclass and later create PV / PVC based on it. However, there is something called "manual provisioning". Which you did in this case.

手动配置是指您需要先手动创建PV，然后再创建具有匹配的spec.storageClassName:字段的PVC.例子:

Manual provisioning is when you need to manually create a PV first, and then a PVC with matching spec.storageClassName: field. Examples:

• 如果创建不带default storageclass，PV和storageClassName参数的PVC(afaik kubeadm不提供默认的storageclass)-PVC将卡在Pending上，并带有事件:此事件没有持久卷可用声明并且未设置存储类别.
• 如果您创建具有default storageclass setup on cluster但不具有storageClassName参数的PVC，它将基于默认的存储类来创建它.
• 如果使用storageClassName参数(在Cloud，Minikube或kubeadm中的某个地方)创建PVC，则PVC也将成为Pending，并显示警告:storageclass.storage.k8s.io手动". 但是，如果使用相同的storageClassName参数创建PV，则将在一段时间内绑定它.

• If you create a PVC without default storageclass, PV and storageClassName parameter (afaik kubeadm is not providing default storageclass) - PVC will be stuck on Pending with event: no persistent volumes available for this claim and no storage class is set.
• If you create a PVC with default storageclass setup on cluster but without storageClassName parameter it will create it based on default storageclass.
• If you create a PVC with storageClassName parameter (somewhere in the Cloud, Minikube or kubeadm) - PVC will also be Pending with the warning: storageclass.storage.k8s.io "manual" not found. However, if you create PV with the same storageClassName parameter, it will be bound in a while.

示例:

$ kubectl get pv,pvc
NAME                              CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   REASON   AGE
persistentvolume/task-pv-volume   10Gi       RWO            Retain           Available           manual                  4s

NAME                        STATUS    VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/pv1   Pending                                      manual         4m12s

...

kubectl get pv,pvc
NAME                              CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM         STORAGECLASS   REASON   AGE
persistentvolume/task-pv-volume   10Gi       RWO            Retain           Bound    default/pv1   manual                  9s

NAME                        STATUS   VOLUME           CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/pv1   Bound    task-pv-volume   10Gi       RWO            manual         4m17s

manual provisioning的缺点是您必须为每个PVC创建PV.如果使用storageclass，则只需创建PVC.

The disadvantage of manual provisioning is that you have to create PV for each PVC. If you use storageclass you can just create PVC.

如果是这样，您能告诉我原因和方式吗?或任何指针.

If so, can you tell me why and how? or any pointer.

您可以使用文档示例或查看 K8s API 自定义您的storageclass.

You can use documentation examples or check here. As you are using cloud with default storageclass you can export it to yaml by:
$ kubectl get sc -oyaml >> storageclass.yaml. Or if you have more than one, you have to specify which one. Names of storageclass can be obtained by
$ kubectl get sc. Later you can refer to K8s API to customize your storageclass.

请注意，PV可根据要求提供10Gi和PVC的存储容量 容量为1Gi，但PVC仍绑定了10Gi容量?

Notice the PV has storage capacity of 10Gi and PVC with request capacity of 1Gi, but still PVC was bound with 10Gi capacity?

您手动创建了具有10Gi的PV，PVC请求了1Gi.由于PVC和PV的边界为1:1，因此PVC寻找一个满足所有条件的PV并绑定到该PV. PVC(pv1)请求了1Gi，PV(task-pv-volume)满足了这些要求，因此Kubernetes对其进行了绑定.不幸的是，在这种情况下，很多空间都被浪费了.

You created manually a PV with 10Gi and the PVC requested 1Gi. As PVC and PV are bounding 1:1, PVC searched for a PV which meets all conditions and bound to it. PVC (pv1) requested 1Gi and the PV (task-pv-volume) meet those requirements so Kubernetes bound them. Unfortunately much of the space was wasted in this case.

我不能与其他PVC共享相同的PV容量

Can't i share the same PV capacity with other PVCs

不幸的是，您无法将2个PVC绑定到1个PV，因为PVC和PV之间的关系是1:1，但是您可以配置许多吊舱/部署以使用同一PVC.

Unfortunately, you cannot bound 2 PVC to 1 PV as the relationship between PVC and PV is 1:1, but you can configure many pods/deployments to use the same PVC.

我建议您查看此stackoverflow情况，因为它很好地说明了AccessMode的具体情况.

I can advise you to look at this stackoverflow case as it explains very well AccessMode specifics.

如果我必须根据要求为不同的PVC创建不同的PV 容量，我是否还需要创建storageclass?或相同的存储 类并使用选择器选择相应的PV?

If i have to create different PVs for different PVC with the required capacity, do i have to create storageclass as-well? Or same storage class and use selectors to select corresponding PV?

正如我之前提到的，如果手动创建具有特定大小的PV并绑定了PVC，而对PVC的请求较少，则会浪费额外的空间.因此，您必须使用相同的资源请求创建PV和PVC，或者让storageclass根据PVC请求调整存储空间.

As I mentioned before, if you create PV manually with a specific size and a PVC bounded to it, which request less, the extra space will be wasted. So, you have to create PV and PVC with the same resource request, or let storageclass adjust the storage based on PVC request.

这篇关于Kubernetes PVC共享一个PV?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！