Schedule Volumes by Label

Volume scheduling based on drive labels

DirectPV offers multiple ways to restrict how volumes schedule to drives:

Available drive space
Node topology with affinity and anti-affinity and similar tools
User-defined drive labels

You can assign labels to classify types of drives. Once assigned, use those labels in storage class parameters to select the desired types.

By default, the DirectPV drives do not have any user-defined labels set on them. Use kubectl directpv label drives to set user-defined labels for DirectPV drives.

Labeling only limits scheduling when creating new volumes as this is a schedule time process.

Tutorial

Throughout this tutorial, replace the place holders <label-key>,<label-value> and <drive-name> with appropriate values based on the classification you chose

Set the label on the DirectPV drive(s).

kubectl directpv label drives <label-key>=<label-value> --drives /dev/<drive-name>

Verify that the labels are properly set by using the list command with the --show-labels flag.
```
kubectl directpv list drives --drives /dev/<drive-name> --show-labels
```

Create or modify the storage class definition.

Set a parameter value in the definition YAML. The value should follow the form directpv-min-io/<label-key>: <label-value>.

parameters:
  directpv.min.io/<label-key>: <label-value>

Refer to the default storage class kubectl get storageclass directpv-min-io -n directpv -o yaml to compare and check if all the fields are present on the new storage class.

The following YAML is an example of a storage class definition that includes a parameters section:

allowVolumeExpansion: false
allowedTopologies:
- matchLabelExpressions:
  - key: directpv.min.io/identity
    values:
    - directpv-min-io
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  finalizers:
  - foregroundDeletion
  labels:
    application-name: directpv.min.io
    application-type: CSIDriver
    directpv.min.io/created-by: kubectl-directpv
    directpv.min.io/version: v1beta1
  name: directpv-min-io-new # Define any storage class name of your choice
  resourceVersion: "511457"
  uid: e93d8dab-b182-482f-b8eb-c69d4a1ec62d
parameters:
  fstype: xfs
  directpv.min.io/<label-key>: <label-value>
provisioner: directpv-min-io
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer

Deploy the workload with the new storage class name set.

Volumes are only placed on the labeled drives. You can verify this with the following command:
```
kubectl directpv list drives --labels <label-key>:<label-value>
kubectl directpv list volumes
```