Before You Begin

MapR Parameters for Dynamic Provisioning

In dynamic provisioning, you can specify MapR parameters for the MapR volume to be created. For a list of the MapR parameters that you can use, see volume create. Note these considerations for using the MapR parameters:

Volume attributes must be represented as a string (enclosed within quotations). Using an integer or boolean is not supported. In the following example, the aetype attribute will generate an error because the value (1) is not enclosed in quotations.
```
namePrefix: "pv"
mountPrefix: "/pv"
type: "rw"
advisoryquota: "100M"
aetype: 1
```
The following MapR parameters are ignored because they are redundant or not supported in the Kubernetes implementation:
- mount
- quota*
- createparent
- path
- name

*Specifying resources: requests: storage in a PersistentVolumeClaim (PVC) (see Example: Mounting a PersistentVolume for Static Provisioning Using the FlexVolume Driver) makes it unnecessary to set the MapR quota parameter.

Kubernetes Access Modes

Kubernetes access modes control how a PersistentVolume (PV) is mounted on the host. Access modes can be specified on both PVs and PVCs. Only Volumes with a matching Access Mode will be bound to a PVC. Unfortunately, beyond the PVC/PV binding behavior, PVs using FlexVolume drivers ignore these access modes in the current version of Kubernetes. All access modes will work with the MapR Data Fabric for Kubernetes. However, they will appear the same. This means the ROX mode will not make the volume read only. If you want read-only behavior, specify readOnly: in the FlexVolume driver flags.

PersistentVolumeClaim Protection

PVC protection is a Kubernetes 1.9 alpha feature that restricts the user from deleting a PVC while it is being used by an active Pod. Alpha features are not tested for use with the volume plug-in and provisioner. However, without PVC protection, you should not delete a PVC that is still attached to Pods. If you have not turned on PVC protection, ensure that you do not delete PVC’s that are in use. In the current release of the MapR Data Fabric for Kubernetes, deleting a PVC causes undefined behavior.

Reclaim Policy

The Kubernetes reclaimPolicy parameter controls what happens to a PersistentVolume if the corresponding PersistentVolumeClaim is deleted. The Recycle Reclaim Policy is not supported by Kubernetes FlexVolume Drivers, so it cannot be used with KDF. The Retain Policy is currently broken in Kubernetes 1.9 StoragePolicies but not in static PersistentVolumes. The MapR Data Fabric for Kubernetes has a workaround that allows Retain policy on dynamically provisioned volumes by passing the reclaimPolicy: in the parameters rather than in the standard place that FlexVolumes ignore. You can specify the reclaim policy normally when you configure a persistent volume.

The following table shows the supported values for the reclaim policy:

Reclaim Policy Value	Description	Support
Delete (default value)	The PersistentVolume and the MapR volume are deleted when the user deletes the corresponding PersistentVolumeClaim.	Supported
Retain	The PersistentVolume and the MapR volume are not deleted when the user deletes the corresponding PersistentVolumeClaim.	Supported*
Recycle	Performs a basic scrub on a PersistentVolume and makes it available for a new PersistentVolumeClaim.	Not Supported by Kubernetes Flexvolumes

*Not supported for dynamic provision without a workaround.

For more information about the reclaim policy, see Change the Reclaim Policy of a PersistentVolume.

Kubernetes Mount Options

The Kubernetes mountOptions parameter is not supported for use with the MapR Data Fabric for Kubernetes because it is not supported for use with the FlexVolume plug-in.