## Known Issues

### Deprecation of FlexVolume

FlexVolume is deprecated. Out-of-tree CSI driver is the recommended way to write volume drivers in Kubernetes.
See [this doc](https://github.com/kubernetes/community/blob/master/sig-storage/volume-plugin-faq.md#kubernetes-volume-plugin-faq-for-storage-vendors) for more information.
Maintainers of FlexVolume drivers should implement a CSI driver and move users of FlexVolume to CSI.

	config.Lock()
	defer config.Unlock()

	var ok bool
	// Lookup in-memory drivercache
	d, ok = config.drivercache[tierName]
	if ok {
		return d, nil
	}

	// Initialize driver from tier config matching tierName
	t, ok := config.Tiers[tierName]
	if !ok {
		return nil, errTierNotFound
	}
	d, err = newWarmBackend(ctx, t, false)
	if err != nil {
		return nil, err
	}

* ACTION REQUIRED: Removes defaulting of CSI file system type to ext4. All the production drivers listed under https://kubernetes-csi.github.io/docs/drivers.html were inspected and should not be impacted after this change. If you are using a driver not in that list, please test the drivers on an updated test cluster first. ([#65499](https://github.com/kubernetes/kubernetes/pull/65499), [@krunaljain](https://github.com/krunaljain))

Fixed kubelet so it would no longer crash when a DRA(Dynamic Resource Allocation) driver returns a nil as part of the Node(Un)PrepareResources response instead of an empty struct (Did not affect drivers written in Go, first showed up with a driver written in Rust). returns a nil as part of the Node(Un)PrepareResources response instead of an empty struct (did not affect drivers written in Go, first showed up with a driver written in Rust). ([#124091](https://github.com/kubernetes/kubernetes/pull/124091),...

- Promote CSIMigrationOpenStack to Beta (off by default since it requires installation of the OpenStack Cinder CSI Driver. The in-tree AWS OpenStack Cinder driver "kubernetes.io/cinder" was deprecated in 1.16 and will be removed in 1.20. Users should enable CSIMigration + CSIMigrationOpenStack features and install the OpenStack Cinder CSI Driver (https://github.com/kubernetes/cloud-provider-openstack) to avoid disruption to existing Pod and PVC objects at that time. Users should...

- kubelet + DRA: For DRA driver plugins (and only for those!), the kubelet now supports a rolling update with `maxSurge > 0` in the driver's DaemonSet. A DRA driver must support this, which can be done via the k8s.io/dynamic-resource-allocation/kubeletplugin helper package. ([#129832](https://github.com/kubernetes/kubernetes/pull/129832), [@po...

- kube-scheduler removed `AzureDiskLimits` ,`CinderLimits` `EBSLimits` and `GCEPDLimits` plugin. Given the corresponding CSI driver reports how many volumes a node can handle in NodeGetInfoResponse, the kubelet stores this limit in CSINode and the scheduler then knows the limit of the driver on the node. Removed plugins AzureDiskLimits, CinderLimits, EBSLimits and GCEPDLimits if you explicitly enabled them in the scheduler config. ([#124003](https://githu...

- Prevented Pods from being scheduled onto nodes that lack the required CSI driver. ([#135012](https://github.com/kubernetes/kubernetes/pull/135012), [@gnufied](https://github.com/gnufied)) [SIG API Machinery, Scheduling, Storage and Testing]

- Set CSIMigrationvSphere feature gates to beta.
  Users should enable CSIMigration + CSIMigrationvSphere features and install the vSphere CSI Driver (https://github.com/kubernetes-sigs/vsphere-csi-driver) to move workload from the in-tree vSphere plugin "kubernetes.io/vsphere-volume" to vSphere CSI Driver.