The default driver with Block Storage service is the internal LVM software iSCSI driver. This is the volume back-end which manages local volumes.
However, the Cinder iSCSI LVM driver has significant performance issues. In production environments, with high I/O activity, there are many potential issues which could affect performance or data integrity,
Red Hat strongly recommends using a certified Block Storage plug-in provider for storage in a production environment. The software iSCSI LVM driver should be used and is only supported for single node evaluations and proof of concept environments.