pv与pvc

目的： 为了屏蔽底层存储实现的细节, 让用户方便使用同时让管理员方便管理, 引入了pv与pvc两种资源对象实现对存储的管理子系统

pv: 对底层网络共享存储的抽象, 将共享存储定义为一种资源

pvc: 用户对存储资源的一个神奇, 就像pod消费node资源一样, pvc能够消费pv资源, pvc可以申请特定存储空间和访问模式

StorageClass ：标记存储资源的特性和性能, 在1.6版本, StorageClass与动态资源供应的机制得到了完善, 实现了存储卷的按需创建

pv详解

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv1
spec:
  capacity:
    storage: 5Gi
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Recycle
  mountOptions:
    - hard
    - nolock
    - nfsvers=3
  nfs:
    path: /tmp
    server: 172.17.0.2

配置参数

capacity：存储空间
volume mode： 存储模式, volumeMode=Filesystem, 包含Filesystem(文件系统)和Block（块设备）
accessModes访问模型
    ReadWriteOnce: 读写权限, 并且只能被单个node挂载
    ReadOnlyMany : 只读权限, 允许被多个node挂载
    ReadWriteMany : 读写权限，允许被多个node挂载

reclaim policy： 回收策略, pvc和pv解绑,删除了pvc, pv里面的数据是否还保留
    Retain: 保留数据, 需要手工删除
    recycle: 回收, 删除里面的数据
    delete: pv自杀
mountOptions:挂载参数

pv生命周期

    available : 表示当前的pv没有被绑定
    bound:  已经被pvc挂载
    released:  pvc没有在使用pv, 需要管理员手工释放pv
    failed： 资源回收失败

pvc详解

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: myclaim
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 8Gi
  storageClassName: slow
  selector:
    matchLabels:
      release: "stable"
    matchExpressions:
      - {key: environment, operator: In, values: [dev]}

参数详解

accessModes: 申请的访问模式必须与pv相同
resources: 资源请求, 既空间大小
storageClassName:  存储类别,
selector: 根据标签选择器把pvc与pv进行绑定, 动态创建pv不适合配置选择器, 

注意： pv与pvc都受限于namespace, 只有相同namespace的pv丶pvc才能绑定, 同样pod与pvc和pv在同一个namespace才能挂载

案例演示： 手工创建pv与pvc

1. 安装nfs：省略
   
   2.创建pv

apiVersion: v1
kind: PersistentVolume
metadata:
  name: nfs-pv001
  labels:
    name: nfs-pv001
spec:
  nfs:
    path: /data/nfs/vol1
    server: 192.168.1.48
  accessModes: ["ReadWriteMany","ReadWriteOnce"]
  persistentVolumeReclaimPolicy: Recycle
  capacity:
    storage: 2Gi
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: nfs-pv002
  labels:
    name: nfs-pv002
spec:
  nfs:
    path: /data/nfs/vol2
    server: 192.168.1.48
  accessModes: ["ReadWriteOnce"]
  capacity:
    storage: 5Gi
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: nfs-pv003
  labels:
    name: nfs-pv003
spec:
  nfs:
    path: /data/nfs/vol3
    server: 192.168.1.48
  accessModes: ["ReadWriteOnce"]
  capacity:
    storage: 10Gi

3.创建pvc

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc001
  namespace: default
spec:
  accessModes: ["ReadWriteOnce"]
  resources:
    requests:
      storage: 1Gi

4.创建pod

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  namespace: default
  labels:
    app: nginx
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.12
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 80
        volumeMounts:
        - name: html
          mountPath: /usr/share/nginx/html
      volumes:
      - name: html
        persistentVolumeClaim:
          claimName: pvc001