install cStor get block devices miss a node

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Use helm install openebs-3.3.1 , follow this to install

helm install openebs openebs-3.3.1.tgz --set cstor.enabled=true -n openebs

install success

kubectl get pod -n openebs

NAME                                            READY   STATUS    RESTARTS   AGE
openebs-cstor-admission-server-b74f5487-r2lrj   1/1     Running   0          32s
openebs-cstor-csi-controller-0                  6/6     Running   0          32s
openebs-cstor-csi-node-5r4xx                    2/2     Running   0          32s
openebs-cstor-csi-node-hkzg6                    2/2     Running   0          32s
openebs-cstor-csi-node-mzm7m                    2/2     Running   0          32s
openebs-cstor-cspc-operator-84464fb479-jz7p4    1/1     Running   0          32s
openebs-cstor-cvc-operator-646f6f676b-l4kph     1/1     Running   0          32s
openebs-localpv-provisioner-77c9bcfd96-jbjsr    1/1     Running   0          32s
openebs-ndm-hx96r                               1/1     Running   0          32s
openebs-ndm-md4m2                               1/1     Running   0          32s
openebs-ndm-operator-5d55748dfd-dhqt6           1/1     Running   0          32s
openebs-ndm-xd5v8                               1/1     Running   0          32s

before Creating cStor storage pools , I check the block device.

kubectl get bd -n openebs
NAME                                           NODENAME                                      SIZE            CLAIMSTATE   STATUS   AGE
blockdevice-102253af77d45d264eaac2e2d5ba230b   server-cdf0266c-393f-471c-b29b-51004e99c426   2147482582528   Unclaimed    Active   34d
blockdevice-75c32e88c24d26a489e27a7b329edd38   server-605ae265-df2b-4e91-9efa-19069d84f2d0   2147482582528   Unclaimed    Active   34d

But I have three worker nodes

kubectl get nodes
NAME                                          STATUS   ROLES                      AGE   VERSION
server-44904695-b3bc-4721-8bad-725d6497a69a   Ready    controlplane,etcd,worker   34d   v1.19.6
server-605ae265-df2b-4e91-9efa-19069d84f2d0   Ready    controlplane,etcd,worker   34d   v1.19.6
server-cdf0266c-393f-471c-b29b-51004e99c426   Ready    controlplane,etcd,worker   34d   v1.19.6

Question:
And I can't found any description about stripe and mirror for the dataRaidGroupType in CStorPoolCluster

What does they mean ? What's different between stripe and mirror？

openebs can get all the infomation. Why openebs can't auto maintain the CStorPoolCluster by itself ?