Creating Storage Volumes

The default Metacloud Block Storage service implementation is an iSCSI solution for Linux.

The Metacloud Block Storage service is not a shared storage solution like a Network Attached Storage (NAS) of NFS volumes where you can attach a volume to multiple servers. With the Metacloud Block Storage service, you can attach a volume to only one instance at a time.

The Metacloud Block Storage service also provides drivers that enable you to use several vendors’ back-end storage devices in addition to the base storage implementation.

These storage devices can be used instead of the base storage installation. The network mode does not interfere with Metacloud Block Storage operations, but you must have networking set up for Block Storage to work. For details, see Networking Overview.

To create and attach volumes to an instance:

  1. Create a volume.

    openstack volume create <VOLUME> -- size <SIZE_IN_GB>
    
  2. Attach the volume to an instance.

    openstack server add volume <SERVER_NAME> <VOLUME_ID>
    

    This command creates a unique IQN that is exposed to the compute node.

    • The compute node, which runs the instance, now has an active iSCSI session and new local storage (usually a /dev/sdX disk).
    • Libvirt uses that local storage as storage for the instance. The instance gets a new disk (usually a /dev/vdX disk).

Note
See Launching an Instance from a Volume for more information.