Chapter 6. Dynamic storage using the LVMS plugin

• The total storage size that you can provision is limited by the size of the underlying Logical Volume Manager (LVM) thin pool and the over-provisioning factor.

• The size of the logical volume depends on the size of the Physical Extent (PE) and the Logical Extent (LE).

  • You can define the size of PE and LE during the physical and logical device creation.
  • The default PE and LE size is 4 MiB.
  • If the size of the PE is increased, the maximum size of the LVM is determined by the kernel limits and your disk space.
  • The size limit for Red Hat Enterprise Linux (RHEL) 9 by using the default PE and LE size is 8 EB.

  • The following are the minimum storage sizes that you can request for each file system type:

    • block: 8 MiB
    • xfs: 300 MiB
    • ext4: 32 MiB

Procedure

• To create the lvmd.yaml configuration file, run the following command:

  $ sudo cp /etc/microshift/lvmd.yaml.default /etc/microshift/lvmd.yaml

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Procedure

• To provision and mount a logical volume to a pod, run the following command:

  $ cat <<EOF | oc apply -f -
  kind: PersistentVolumeClaim
  apiVersion: v1
  metadata:
    name: my-lv-pvc
  spec:
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 1G
  ---
  apiVersion: v1
  kind: Pod
  metadata:
    name: my-pod
  spec:
    containers:
    - name: nginx
      image: nginx
      command: ["/usr/bin/sh", "-c"]
      args: ["sleep", "1h"]
      volumeMounts:
      - mountPath: /mnt
        name: my-volume
      securityContext:
        allowPrivilegeEscalation: false
        capabilities:
          drop:
            - ALL
        runAsNonRoot: true
        seccompProfile:
          type: RuntimeDefault
    volumes:
      - name: my-volume
        persistentVolumeClaim:
          claimName: my-lv-pvc
  EOF

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