Provisioning Read-Write-Many (RWX) PVCs
NFS server provisioner stable helm chart is widely used for deploying NFS servers on Kubernetes cluster. This server provides PVCs in RWX mode so that multiple web applications can access the data in a shared fashion. OpenEBS cStor volumes are used as persistent backend storage for these nfs servers to provide a scalable and manageable RWX shared storage solution.
OpenEBS Dynamic NFS Provisioner
OpenEBS includes an alpha version of OpenEBS Dynamic NFS provisioner that allows users to create an NFS PV that sets up an new Kernel NFS instance for each PV on top of users choice of backend storage.
This project is currently under active development. For getting started and getting involved in developing this project, check out https://github.com/openebs/dynamic-nfs-provisioner.
The rest of this document contains instructions about the NFS server provisioner maintained by the Kubernetes SIGs community.
Below are advantage of using NFS provisioner over OpenEBS cStor volumes
- NFS data is replicated, highly available across zones if configured accordingly
- Data is thin provisioned. Persistent volume mounts are configured at the required size and cStor physical pools can be started with as low as one disk per pool instance and grow as the storage is used up
#Setting up a single NFS server
Select or create a cStor pool
Select or create a cStor pool that satisfies the performance, and availability requirements
Select or create a cStor storage Class
Create a storage class to point to the above selected pool and also select number of replicas and default size of the volume.
Create a namespace for deploying NFS server provisioner
Deploy NFS server provisioner
Deploy NFS server provisioner into the above namespace using stable helm chart. Pass the following main parameter values.
- namespace: Namespace for the NFS server provisioner which you have created in the previous section.
- name: Release name for helm installation.
- persistence.storageClass: StorageClass used for provisioning cStor volume.
- persistence.size: cStor volume size which will be used for running nfs provisioner.
- storageClass.name: Provide a name for NFS StorageClass to be created which can be used by the web application PVCs.
An example helm install command is
Note: It is recommended that the OpenEBS storage class specifies 10% more space than what is required by the RWX PVC. For example, if RWX PVC requires 100G, then provision cStor volume with 110G.
Provision RWX volume using the PVC
Use the StorageClass which is created in above command and create a new PVC and use the volume in your applications.
#Setting up multiple NFS servers
When multiple NFS shares are needed, use multiple NFS provisioners. Each NFS server manages one NFS server. Same or different OpenEBS StorageClass can be used for multiple NFS provisioners.