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Device classes

To define custom storage groups, create custom device classes by adding a device-classes array to your logical volume manager storage (LVMS) configuration. With this configuration, you can enable MicroShift to categorize devices based on your specific storage requirements.

Add the array to the /etc/microshift/lvmd.yaml configuration file. A single device class must be set as the default. You must restart MicroShift for configuration changes to take effect.

Removing a device class while there are still persistent volumes or VolumeSnapshotContent objects connected to that device class breaks both thick and thin provisioning.

You can define multiple device classes in the device-classes array. These classes can be a mix of thick and thin volume configurations.

Example of a mixed device-class array

socket-name: /run/topolvm/lvmd.sock
device-classes:
  - name: ssd
    volume-group: ssd-vg
    spare-gb: 0
    default: true
  - name: hdd
    volume-group: hdd-vg
    spare-gb: 0
  - name: thin
    spare-gb: 0
    thin-pool:
      name: thin
      overprovision-ratio: 10
    type: thin
    volume-group: ssd
  - name: striped
    volume-group: multi-pv-vg
    spare-gb: 0
    stripe: 2
    stripe-size: "64"
    lvcreate-options:

device-classes.spare-gb`: Specifies the spare capacity. When you set this value to anything other than 0, more space can be allocated than expected.
device-classes.lvcreate-options: Specifies extra arguments to pass to the lvcreate command, such as --type=<type>. Neither MicroShift nor the LVMS verifies lvcreate-options values. These optional values are passed as is to the lvcreate command. Ensure that the options specified here are correct.