Note the comments in the yaml configuration file, and the indentation of the format
I.
1.Persistent Volume, or PV, is a network storage that has been configured by an administrator in the cluster, equivalent to a storage volume and a storage disk.Storage classes are automatically managed by administrators or by StorageClass.
2.Persistent Volume Claim, or PVC, is a user storage request, which is equivalent to Pod, which consumes node resources, while PVC consumes storage resources. Generally speaking, pv is the total space created, and PVC requests space use from the total space.
3. Access Control Types for PVs:
(1)ReadWriteOnce: Access mode is to mount to a single node read-write only
(2)ReadWriteMany: Access mode is to mount to multiple nodes only in read-write mode
(3)ReadOnlyOnce: Access mode is to mount to a single node only in a read-only manner
4.PV's space recycling strategy (persistentVolumeReclaimPolicy):
(1)Recycle: Clear data automatically.
(2)Retain: Manual recycling by an administrator is required.
(3)Delete: Cloud storage dedicated.
5.PV and PVC are related to each other by accessModes and storageClassName.
2. Simulate the effect of data persistence using MySQL experiment:
**1.First set up NFS Shared Services:** 1.[root@master ~]# yum install -y nfs-utils rpcbind #Note here that all three install NFS services. 2.[root@master ~]# vim /etc/exports 3./nfsdata *(rw,sync,no_root_squash) 4.[root@master ~]# mkdir /nfsdata 5.[root@master ~]# systemctl start rpcbind 6.[root@master ~]# systemctl start nfs-server.service 7.[root@master ~]# showmount -e 8.Export list for master: 9./nfsdata *
**2.Establish PV Resource object:** 1.[root@master ~]# mkdir yaml 2.[root@master ~]# cd yaml/ 3.[root@master yaml]# vim nfs-pv.yaml 4. 5.apiVersion: v1 6.kind: PersistentVolume 7.metadata: 8. name: lbh-pv 9.spec: 10. capacity: 11. storage: 1Gi 12. accessModes: 13. - ReadWriteOnce #Access mode is that a single node can only be mounted read-write. 14. persistentVolumeReclaimPolicy: Retain #The PV space recycling strategy is manual recycling. 15. storageClassName: nfs #Define the name of the storage class 16. nfs: 17. path: /nfsdata/lbh-pv 18. server: 192.168.2.50
Execute the yaml file to see the status: 1.[root@master yaml]# kubectl apply -f nfs-pv.yaml 2.persistentvolume/lbh-pv created 3.[root@master yaml]# kubectl get pv 4.NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE 5.lbh-pv 1Gi RWO Retain Available nfs 27s Note the state of PV Available:**
The PV was created successfully.
**3.Establish PVC Resource object:** 1.[root@master yaml]# vim nfs-pvc.yaml 2. 3.apiVersion: v1 4.kind: PersistentVolumeClaim 5.metadata: 6. name: lbh-pvc 7.spec: 8. accessModes: 9. - ReadWriteOnce #The access mode here must be consistent with the PV resource 10. resources: 11. requests: 12. storage: 1Gi 13. storageClassName: nfs #Storage class name, must match PV resource
**implement yaml File, View PVC and PV Status:** 1.[root@master yaml]# kubectl apply -f nfs-pvc.yaml 2.persistentvolumeclaim/lbh-pvc created 3.[root@master yaml]# kubectl get pv 4.NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE 5.lbh-pv 1Gi RWO Retain **Bound ** default/lbh-pvc nfs 3m55s 6.[root@master yaml]# kubectl get pvc 7.NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE 8.lbh-pvc ** Bound** lbh-pv 1Gi RWO nfs 10s ```Notice if it is related Bound:
4. Create Deployment resource object, mirrored as mysql:5.6
Node downloads mirror in advance:
1.[root@node01 ~]# docker pull mysql:5.6
2.[root@node02 ~]# docker pull mysql:5.6
**Establish Deployment Resource object:** 1.[root@master yaml]# vim mysql.yaml 2. 3.apiVersion: extensions/v1beta1 4.kind: Deployment 5.metadata: 6. name: lbh-mysql 7.spec: 8. selector: 9. matchLabels: 10. app: mysql 11. template: 12. metadata: 13. labels: 14. app: mysql 15. spec: 16. containers: 17. - image: mysql:5.6 18. name: mysql 19. env: #Define variables, where the password for the MySQL database is defined 20. - name: MYSQL_ROOT_PASSWORD 21. value: 123.com 22. volumeMounts: 23. - name: mysql-storage 24. mountPath: /var/lib/mysql #The database's data store directory, which is persisted 25. volumes: 26. - name: mysql-storage 27. persistentVolumeClaim: 28. claimName: lbh-pvc #Specify PVC resources.
**implement yaml File, view status:** 1.[root@master yaml]# kubectl apply -f mysql.yaml 2.deployment.extensions/lbh-mysql created 3.[root@master yaml]# kubectl get pod 4.NAME READY STATUS RESTARTS AGE 5.lbh-mysql-59778fd8d6-xhk7h 0/1 ContainerCreating 0 3m7s
** Containers are always being created at this time and can be troubleshooted in four ways: (1) Use the kubectl describe command to view the details of the Pod. (2) Use the kubectl logs command to view Pod's logs, since the container was not created successfully, no logs exist. (3) View local message logs (4) View kubelet's log.** Use the kubectl describe command to view Pod details: [root@master yaml]# kubectl describe pod lbh-mysql-59778fd8d6-xhk7h Last message: mount.nfs: mounting 192.168.2.50:/nfsdata/lbh-pv failed, reason given by server: No such file or directory As prompted, the specified directory does not exist when mounting the NFS storage directory. Do a directory creation and review the Pod's status again: 1.[root@master yaml]# mkdir -p /nfsdata/lbh-pv 2.[root@master yaml]# kubectl get pod 3.NAME READY STATUS RESTARTS AGE 4.lbh-mysql-59778fd8d6-xhk7h 1/1 Running 0 12m
Deployment resource created successfully.
**5. Enter MySQL database to create test data.** 1.[root@master yaml]# kubectl exec -it lbh-mysql-59778fd8d6-xhk7h -- mysql -uroot -p123.com 2.mysql> show databases; #view database. 3.+--------------------+ 4.| Database | 5.+--------------------+ 6.| information_schema | 7.| mysql | 8.| performance_schema | 9.+--------------------+ 10.3 rows in set (0.01 sec) 11. 12.mysql> create database lbh; #create database. 13. 14.mysql> use lbh; #Select the database to use. 15.Database changed 16.mysql> create table lbh_id (id int(4)); #create table. 17. 18.mysql> insert lbh_id values(9224); #insert data into the table. 19. 20.mysql> select * from lbh_id; #view all the data in the table. 21.+------+ 22.| id | 23.+------+ 24.| 9224 | 25.+------+ 26.1 row in set (0.00 sec) 27. 28.mysql> exit View data locally: 1.[root@master yaml]# ls /nfsdata/lbh-pv/ 2.auto.cnf ibdata1 ib_logfile0 ib_logfile1 lbh mysql performance_schema Data exists.
**6.See Pod Which node is running, close the corresponding node kubelet，Check to see if recreate Pod，Created Pod Does the data still exist:** 1.[root@master yaml]# kubectl get pod -o wide 2.NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES 3.lbh-mysql-59778fd8d6-xhk7h 1/1 Running 0 26m 10.244.1.4 node01 <none> <none> 4. 5.[root@node01 ~]# systemctl stop kubelet.service 6. 7.[root@master yaml]# kubectl get pod -o wide -w 8.lbh-mysql-59778fd8d6-xhk7h 1/1 Running 0 28m 10.244.1.4 node01 <none> <none> 9.lbh-mysql-59778fd8d6-xhk7h 1/1 Terminating 0 33m 10.244.1.4 node01 <none> <none> 10.lbh-mysql-59778fd8d6-cf6g4 0/1 Pending 0 0s <none> <none> <none> <none> 11.lbh-mysql-59778fd8d6-cf6g4 0/1 Pending 0 0s <none> node02 <none> <none> 12.lbh-mysql-59778fd8d6-cf6g4 0/1 ContainerCreating 0 1s <none> node02 <none> <none> 13.lbh-mysql-59778fd8d6-cf6g4 1/1 Running 0 2s 10.244.2.9 node02 <none>
**Pod Re-create successful, enter Pod To see if the data exists:** 1.[root@master yaml]# kubectl get pod -o wide 2.NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES 3.lbh-mysql-59778fd8d6-cf6g4 1/1 Running 0 12s 10.244.2.10 node02 <none> <none> 4.lbh-mysql-59778fd8d6-xhk7h 1/1 Terminating 0 44m 10.244.1.4 node01 <none> <none> 5. 6.[root@master yaml]# kubectl exec -it lbh-mysql-59778fd8d6-cf6g4 -- mysql -uroot -p123.com 7.mysql> show databases; 8.+--------------------+ 9.| Database | 10.+--------------------+ 11.| information_schema | 12.| lbh | 13.| mysql | 14.| performance_schema | 15.+--------------------+ 16.4 rows in set (0.01 sec) 17. 18.mysql> use lbh 19.Database changed 20.mysql> select * from lbh_id; 21.+------+ 22.| id | 23.+------+ 24.| 9224 | 25.+------+ 26.1 row in set (0.00 sec)
The data still exists, check the local files again: 1.[root@master yaml]# ls /nfsdata/lbh-pv/ 2.auto.cnf ibdata1 ib_logfile0 ib_logfile1 lbh mysql performance_schema
MySQL data persistence complete.