Cinder multi-backend v3

I didn't test end to end but i examined the generated config files for cinder.

Multi-backend with gluster and iscsi enabled, eqlx disabled:

    cinder_backend_eqlx: 'false'
    cinder_backend_eqlx_name: eqlx_backend
    cinder_backend_gluster: 'true'
    cinder_backend_gluster_name: gluster_backend
    cinder_backend_iscsi: 'true'
    cinder_backend_iscsi_name: iscsi_backend
    cinder_db_password: changeme
    cinder_eqlx_chap_login: chapadmin
    cinder_eqlx_chap_password: changeme
    cinder_eqlx_group_name: group-0
    cinder_eqlx_pool: default
    cinder_eqlx_use_chap: 'false'
    cinder_gluster_peers:
    - 192.168.122.11
    cinder_gluster_volume: cinder
    cinder_multiple_backends: 'true'
    cinder_san_ip: 192.168.124.11
    cinder_san_login: grpadmin
    cinder_san_password: changeme
    cinder_san_thin_provision: 'false'
    cinder_user_password: changeme

Relevant parts of cinder.conf:

    enabled_backends=glusterfs,iscsi

    # ... more content here ...

    [iscsi]
    iscsi_ip_address=192.168.122.10
    volume_backend_name=iscsi
    volume_group=cinder-volumes
    iscsi_helper=tgtadm

    [glusterfs]
    volume_backend_name=glusterfs
    glusterfs_shares_config=/etc/cinder/shares.conf
    volume_driver=cinder.volume.drivers.glusterfs.GlusterfsDriver
    glusterfs_mount_point_base=/var/lib/cinder/volumes

shares.conf:

    192.168.122.11:/cinder

------

Single-backend with only gluster:

    cinder_backend_eqlx: 'false'
    cinder_backend_eqlx_name: eqlx_backend
    cinder_backend_gluster: 'true'
    cinder_backend_gluster_name: gluster_backend
    cinder_backend_iscsi: 'false'
    cinder_backend_iscsi_name: iscsi_backend
    cinder_db_password: changeme
    cinder_eqlx_chap_login: chapadmin
    cinder_eqlx_chap_password: changeme
    cinder_eqlx_group_name: group-0
    cinder_eqlx_pool: default
    cinder_eqlx_use_chap: 'false'
    cinder_gluster_peers:
    - 192.168.122.11
    cinder_gluster_volume: cinder
    cinder_multiple_backends: 'false'
    cinder_san_ip: 192.168.124.11
    cinder_san_login: grpadmin
    cinder_san_password: changeme
    cinder_san_thin_provision: 'false'
    cinder_user_password: changeme

Relevant parts of cinder.conf:

    glusterfs_shares_config=/etc/cinder/shares.conf

    # ... more content here ...

    glusterfs_mount_point_base=/var/lib/cinder/volumes

    # ... more content here ...

    volume_driver=cinder.volume.drivers.glusterfs.GlusterfsDriver

shares.conf:

    192.168.122.11:/cinder