# Volume Provisioning The first thing to make use of storage is to provision the volumes. And one might need to provision more than one volumes to fit different use cases. In K8S, there two ways to get a volume provisioned: Static provisioning and Dynamic provisioning. ## Static provisioning * Provision the storage manually by following the instruction from the storage vendor. {% hint style="info" %} If you are using VMware vSphere, you could create VMDK on your vSan datastore ``` * ssh to your esxi host [root@esxi-dell-h:/vmfs/volumes/vsan:52fae366e94edb86-c6633d0af03e5aec] mkdir demo [root@esxi-dell-h:/vmfs/volumes/vsan:52fae366e94edb86-c6633d0af03e5aec] cd demo [root@esxi-dell-h:/vmfs/volumes/vsan:52fae366e94edb86-c6633d0af03e5aec/9cc4ef5c-370b-7eeb-876d-246e962c2408] vmkfstools -c 2G -d thin -W vsan demo.vmdk Create: 100% done. [root@esxi-dell-h:/vmfs/volumes/vsan:52fae366e94edb86-c6633d0af03e5aec/9cc4ef5c-370b-7eeb-876d-246e962c2408] ls demo.vmdk ``` {% endhint %} * Next step is to create the PV which consumes the storage you just created. ``` apiVersion: v1 kind: PersistentVolume metadata: name: demo-pv spec: storageClassName: demo capacity: storage: 2Gi accessModes: - ReadWriteOnce persistentVolumeReclaimPolicy: Retain vsphereVolume: volumePath: "[vsanDatastore] demo/demo.vmdk" fsType: ext4 ``` {% hint style="info" %} `storageClass: demo`is used to bind PVC to this PV. You could have no such StorageClass created before hand. {% endhint %} {% hint style="info" %} `vsphereVolume` is the in-tree volume plugin supported by K8S. More details could be found [here](https://kubernetes.io/docs/concepts/storage/persistent-volumes) {% endhint %} * Next step is to create PVC which could consume PV for a pod. ``` apiVersion: v1 kind: PersistentVolumeClaim metadata: name: demo-pvc spec: storageClassName: demo accessModes: - ReadWriteOnce resources: requests: storage: 2Gi ``` {% hint style="info" %} If the storageClassName does not match the one you used for PV, your PVC will not bind to the PV you just created. {% endhint %} * Use it in Pod or Deployment. The following YAML is just an example for Pod. ``` apiVersion: v1 kind: Pod metadata: name: demo-pod spec: containers: - name: busybox image: "k8s.gcr.io/busybox" volumeMounts: - name: demo-vol mountPath: "/demo" command: [ "sleep", "1000000" ] volumes: - name: demo-vol persistentVolumeClaim: claimName: demo-pvc ``` Follow the tutorial [here](https://kubernetes.io/docs/tasks/configure-pod-container/configure-persistent-volume-storage/) if you would like to use minikube to do some experiments. Above is the steps you would use to manually provision a storage/volume. ## Dynamic provisioning ### Why dynamic provision * Before dynamic provisioning, cluster administrators had to manually make calls to their cloud or storage provider to provision new storage volumes, and then create PersistentVolume objects to represent them in Kubernetes. With dynamic provisioning, these two steps are automated, eliminating the need for cluster administrators to pre-provision storage. Instead, the storage resources can be dynamically provisioned using the provisioner specified by the StorageClass object. * Better resource management ? ### End to end workflow (Bottom up) * Create `StorageClass` ``` kind: StorageClass apiVersion: storage.k8s.io/v1 metadata: name: demo-sc-vsan provisioner: kubernetes.io/vsphere-volume parameters: storagePolicyName: gold datastore: vsanDatastore ``` The `provisioner` specifies what volume plugin to be used for dynamic provisioning. The volume plugin is in charge of create and setup the VMDK in the vSphere example, and also create the PV automatically. Differnt vendor has different implementations. {% hint style="info" %} * The provisioner has `kubernetes.io` as prefix is the in-tree volume plugin. Its implementation could be found at `kubernetes/pkg/volume/vsphere_volume/vsphere_volume.go` from `https://github.com/kubernetes/kubernetes.git` * The provisioner used above is the in-tree provisioner, more about provisioner for the external storage provisioner could be found [here](https://kubernetes.io/docs/concepts/storage/storage-classes/#provisioner). * What is CSI could be found [here](/notebook/k8s-related/k8s-storage/understand-csii.md). {% endhint %} * Create PVC ``` apiVersion: v1 kind: PersistentVolumeClaim metadata: name: demo-sc-pvc spec: storageClassName: demo-sc-vsan accessModes: - ReadWriteOnce resources: requests: storage: 2Gi ``` Once the PVC is created, it will find the storageclass for dynamic provisioning. The storageClassName must match the StorageClass created in step #1. {% hint style="info" %} The design of volume provisioning could be found [here](https://github.com/kubernetes/community/blob/master/contributors/design-proposals/storage/volume-provisioning.md). {% endhint %} * Pod or Deployment uses the PVC ``` apiVersion: v1 kind: Pod metadata: name: demo-sc-pod spec: containers: - name: busybox image: "k8s.gcr.io/busybox" volumeMounts: - name: demo-vol mountPath: "/demo" command: [ "sleep", "1000000" ] volumes: - name: demo-vol persistentVolumeClaim: claimName: demo-sc-pvc ``` Other references: {% embed url="" %} {% embed url="" %} {% embed url="" %} --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://daniel-guo.gitbook.io/notebook/k8s-related/k8s-storage/provisioning.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.