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>
Currently controller picks one node and the node agent keeps on trying to
create the volume on that node. There might not be enough space available
on that node to create the volume.
The controller can try on all the nodes sequentially and fail
the request if volume creation fails on all the nodes which satisfies the
topology contraints.
Signed-off-by: Pawan <pawan@mayadata.io>
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>
