Usecase: A node in the Kubernetes cluster is replaced with a new node. The
new node gets a different `kubernetes.io/hostname`. The storage devices
that were attached to the old node are re-attached to the new node.
Fix: Instead of using the default `kubenetes.io/hostname` as the node affinity
label, this commit changes to use `openebs.io/nodeid`. The ZFS LocalPV driver
will pick the value from the nodes and set the affinity.
Once the old node is removed from the cluster, the K8s scheduler will continue
to schedule applications on the old node only.
User can now modify the value of `openebs.io/nodeid` on the new node to the same
value that was available on the old node. This will make sure the pods/volumes are
scheduled to the node now.
Note: Now to migrate the PV to the other node, we have to move the disks to the other node
and remove the old node from the cluster and set the same label on the new node using
the same key, which will let k8s scheduler to schedule the pods to that node.
Other updates:
* adding faq doc
* renaming the config variable to nodename
Signed-off-by: Pawan <pawan@mayadata.io>
Co-authored-by: Akhil Mohan <akhilerm@gmail.com>
* Update docs/faq.md
Co-authored-by: Akhil Mohan <akhilerm@gmail.com>
Applications who want to share a volume can use below storageclass
to make their volumes shared by multiple pods
```yaml
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: openebs-zfspv
parameters:
shared: "yes"
fstype: "zfs"
poolname: "zfspv-pool"
provisioner: zfs.csi.openebs.io
```
Now the provisioned volume using this storageclass can be used by multiple pods.
Here pods have to make sure of the data consistency and have to have locking mechanism.
One thing to note here is pods will be scheduled to the node where volume is present
so that all the pods can use the same volume as they can access it locally only.
This was we can avoid the NFS overhead and can get the optimal performance also.
Also fixed the log formatting in the GRPC log.
Signed-off-by: Pawan <pawan@mayadata.io>
The controller does not check whether the volume has been created or not
and return successful. Which in turn binds the pvc to the pv.
The PVC should not bound until corresponding zfs volume has been created.
Now controller will check the ZFSVolume CR state to be "Ready" before returning
successful. The CSI will retry the CreateVolume request when it will get
a error reply and when the ZFS node agent creates the ZFS volume and sets the
ZFSVolume CR state to be "Ready", the controller will return success for the
CreateVolume Request and then PVC will be bound.
Signed-off-by: Pawan <pawan@mayadata.io>
This commits support snapshot and clone commands via CSI driver. User can create snap and clone using the following steps.
Note:
- Snapshot is created via reconciliation CR
- Cloned volume will be on the same zpool where the snapshot is taken
- Cloned volume will have same properties as source volume.
-----------------------------------
Create a Snapshotclass
```
kind: VolumeSnapshotClass
apiVersion: snapshot.storage.k8s.io/v1beta1
metadata:
name: zfspv-snapclass
annotations:
snapshot.storage.kubernetes.io/is-default-class: "true"
driver: zfs.csi.openebs.io
deletionPolicy: Delete
```
Once snapshotclass is created, we can use this class to create a Snapshot
```
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshot
metadata:
name: zfspv-snap
spec:
volumeSnapshotClassName: zfspv-snapclass
source:
persistentVolumeClaimName: csi-zfspv
```
```
$ kubectl get volumesnapshot
NAME AGE
zfspv-snap 7m52s
```
```
$ kubectl get volumesnapshot -o yaml
apiVersion: v1
items:
- apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshot
metadata:
annotations:
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"snapshot.storage.k8s.io/v1beta1","kind":"VolumeSnapshot","metadata":{"annotations":{},"name":"zfspv-snap","namespace":"default"},"spec":{"source":{"persistentVolumeClaimName":"csi-zfspv"},"volumeSnapshotClassName":"zfspv-snapclass"}}
creationTimestamp: "2020-01-30T10:31:24Z"
finalizers:
- snapshot.storage.kubernetes.io/volumesnapshot-as-source-protection
- snapshot.storage.kubernetes.io/volumesnapshot-bound-protection
generation: 1
name: zfspv-snap
namespace: default
resourceVersion: "30040"
selfLink: /apis/snapshot.storage.k8s.io/v1beta1/namespaces/default/volumesnapshots/zfspv-snap
uid: 1a5cf166-c599-4f58-9f3c-f1148be47fca
spec:
source:
persistentVolumeClaimName: csi-zfspv
volumeSnapshotClassName: zfspv-snapclass
status:
boundVolumeSnapshotContentName: snapcontent-1a5cf166-c599-4f58-9f3c-f1148be47fca
creationTime: "2020-01-30T10:31:24Z"
readyToUse: true
restoreSize: "0"
kind: List
metadata:
resourceVersion: ""
selfLink: ""
```
Openebs resource for the created snapshot
```
$ kubectl get snap -n openebs -o yaml
apiVersion: v1
items:
- apiVersion: openebs.io/v1alpha1
kind: ZFSSnapshot
metadata:
creationTimestamp: "2020-01-30T10:31:24Z"
finalizers:
- zfs.openebs.io/finalizer
generation: 2
labels:
kubernetes.io/nodename: pawan-2
openebs.io/persistent-volume: pvc-18cab7c3-ec5e-4264-8507-e6f7df4c789a
name: snapshot-1a5cf166-c599-4f58-9f3c-f1148be47fca
namespace: openebs
resourceVersion: "30035"
selfLink: /apis/openebs.io/v1alpha1/namespaces/openebs/zfssnapshots/snapshot-1a5cf166-c599-4f58-9f3c-f1148be47fca
uid: e29d571c-42b5-4fb7-9110-e1cfc9b96641
spec:
capacity: "4294967296"
fsType: zfs
ownerNodeID: pawan-2
poolName: zfspv-pool
status: Ready
volumeType: DATASET
kind: List
metadata:
resourceVersion: ""
selfLink: ""
```
Create a clone volume
We can provide a datasource as snapshot name to create a clone volume
```yaml
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: zfspv-clone
spec:
storageClassName: openebs-zfspv
dataSource:
name: zfspv-snap
kind: VolumeSnapshot
apiGroup: snapshot.storage.k8s.io
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 4Gi
```
It will create a ZFS clone volume from the mentioned snapshot and create the PV on the same node where original volume is there.
Here, As resize is not supported yet, the clone PVC size should match the size of the snapshot.
Also, all the properties from the storageclass will not be considered for the clone case, it will take the properties from the snapshot and create the clone volume. One thing to note here is that, the storageclass in clone PVC should have the same poolname as that of the original volume as across the pool, clone is not supported.
Signed-off-by: Pawan <pawan@mayadata.io>
