Metacloud manages storage with three services: Compute (nova), Image (glance), and Block Storage (cinder). Depending on your Metacloud deployment configuration, these services use back end storage that is ephemeral, which exists only when the VM is available, or persistent, which “persists” after the VM is terminated. Persistent storage uses a storage driver like Ceph, NFS, Pure, or SolidFire.
As of the 4.1.5 release, Metacloud provides local server storage to VMs while leveraging Ceph for block and image storage.
The Compute service allocates ephemeral storage to instances at the time of their launch. Each instance requires a root disk for booting and any optional, ephemeral disk based on the flavor used to create the instance. The content for the root disk is based on an image or a persistent Block Storage volume. Your root disk choices, like boot from image, are detailed in the Instance Workflow.
The Image service stores virtual machine images locally in the Metacloud Control Plane (MCP) or in a separate storage system with a Ceph or NFS back end. See Working with Images.
The Block Storage service is a type of persistent storage that uses a block device (volume) that can be formatted and attached to an instance. If your Metacloud includes Volumes on the main menu, then it is configured with a storage driver and you can manage volumes for your instances.
To view the available volume type:
For the Dashboard, the volume type is in the Type drop-down list of the Create Volume dialog box.
For the CLI, list the volume type:
openstack volume type list