Persistent Volumes

Rackspace Spot provides four out-of-the-box storage classes for persistent volumes, in addition to the ephemeral storage available on worker nodes.

Ephemeral Storage

Spot worker nodes have a certain amount of local storage that can be used as ephemeral storage. Please note that this is intended to be available as temporary storage, and data stored here will be lost when nodes are de-provisioned. Ephemeral storage is also not intended to store large amounts of data, since that space must be shared with containers and for other purposes.

Persistent Volume Storage Classes

Spot provides the following storage classes:

Default Storage Class

The 'ssd' storage class is the default in gen-1 datacenters, and will be used if you don't specify an alternate storage class in your persistent volume claim. In gen-2 datacenters, ssdv2-performance is the default storage class.

Creating a Persistent Volume Claim

Here is an example of a persistent volume claim that uses the 'default' storage class for a 7GB PVC:

kind: PersistentVolumeClaim

apiVersion: v1

metadata:

  name: my-minecraft

  labels:

    app: my-minecraft

    chart: "minecraft-4.12.0"

    app.kubernetes.io/name: "minecraft"

    app.kubernetes.io/instance: my-minecraft

    app.kubernetes.io/version: "4.12.0"

  annotations:

    volume.alpha.kubernetes.io/storage-class: default

spec:

  accessModes:

    - ReadWriteOnce

  resources:

    requests:

      storage: "7Gi"

Notable Limitations

1. Note the distinction between gen-2 datacenters and gen-1 datacenters
2. Persistent Volumes <5GB are not currently supported
3. Persistent Volumes between 20GB and 50GB are not currently supported
4. Access mode can only be ReadWriteOnce. ReadWriteMany is not currently supported
   1. This means that the volume can be mounted as read-write by a single node. Multiple pods can access the volume when the pods are running on the same node.