The above storage class tells that ZFS pool "zfspv-pool" is available on nodes zfspv-node1 and zfspv-node2 only. The ZFS driver will create volumes on those nodes only.
Please note that the provisioner name for ZFS driver is "zfs.csi.openebs.io", we have to use this while creating the storage class so that the volume provisioning/deprovisioning request can come to ZFS driver.
The ZFS driver has a scheduler which will try to distribute the PV across the nodes so that one node should not be loaded with the volumes. Currently the driver has
VolumeWeighted scheduling algorithm, in which it will try to find a ZFS pool which has less number of volumes provisioned in it from all the nodes where the ZFS pools are available.
Once it is able to find the node, it will create a PV for that node and also create a ZFSVolume custom resource for the volume with the NODE information. The watcher for this ZFSVolume
CR will get all the information for this object and creates a ZFS dataset(zvol) with the given ZFS property on the mentioned node.
As the scheduler takes into account the count of ZFS volumes only for scheduling decisions, it does not account available cpu or memory or anything while scheduling, so if you want to use node selector/affinity rules on the application pod or have cpu, memory constraints, you should use kubernetes scheduler for that, you can put volumeBindingMode as WaitForFirstConsumer in the storage class for delayed binding, which will make kubernetes scheduler to schedule the POD first then it will ask the ZFS driver to create the PV, the driver, then, will create the PV on the node where the POD is scheduled.
```
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: openebs-zfspv
allowVolumeExpansion: true
parameters:
blocksize: "4k"
compression: "on"
dedup: "on"
thinprovision: "yes"
poolname: "zfspv-pool"
provisioner: zfs.csi.openebs.io
volumeBindingMode: WaitForFirstConsumer
```
Please note that once PV is created for a node, application using that PV will always come to that node only as PV will be stick to that node. The scheduling algorithm by ZFS driver or kubernetes will come into picture only at the deployment time, once PV is created, the application can not move anywhere as the data is there on the node where PV is.
ZFS Volume Property can be changed like compression on/off can be done by just simply editing the kubernetes resource for the corresponding zfs volume by using below command :
for deprovisioning the volume we can delete the application which is using the volume and then we can go ahead and delete the pv, as part of deletion of pv this volume will also be deleted from the ZFS pool and data will be freed.
