Tiramisu: replication group support

https://review.openstack.org/352228
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commit 18744ba1991a7e1599d256857727454bac1ae2d2
Author: xing-yang <email address hidden>
Date: Sat Jul 9 14:26:48 2016 -0400

    Tiramisu: replication group support

    This patch adds support for replication group.
    It is built upon the generic volume groups.
    It supports enable replication, disable replication,
    failover replication, and list replication targets.

    Client side patch is here:
        https://review.openstack.org/#/c/352229/

    To test this server side patch using the client side patch:
    export OS_VOLUME_API_VERSION=3.38

    Make sure the group type has group_replication_enabled or
    consistent_group_replication_enabled set in group specs,
    and the volume types have replication_enabled set in extra specs
    (to be compatible with Cheesecake).

    cinder group-type-show my_group_type
    +-------------+---------------------------------------+
    | Property | Value |
    +-------------+---------------------------------------+
    | description | None |
    | group_specs | group_replication_enabled : <is> True |
    | id | 66462b5c-38e5-4a1a-88d6-7a7889ffec55 |
    | is_public | True |
    | name | my_group_type |
    +-------------+---------------------------------------+

    cinder type-show my_volume_type
    +---------------------------------+--------------------------------------+
    | Property | Value |
    +---------------------------------+--------------------------------------+
    | description | None |
    | extra_specs | replication_enabled : <is> True |
    | id | 09c1ce01-87d5-489e-82c6-9f084107dc5c |
    | is_public | True |
    | name | my_volume_type |
    | os-volume-type-access:is_public | True |
    | qos_specs_id | None |
    +---------------------------------+--------------------------------------+

    Create a group:
    cinder group-create --name my_group my_group_type my_volume_type
    cinder group-show my_group

    Enable replication group on the primary storage:
        cinder group-enable-replication my_group
    Expected results: replication_status becomes “enabled”.

    Failover replication group to the secondary storage.
    If secondary-backend-id is not specified, it will go to the
    secondary-backend-id configured in cinder.conf:
        cinder group-failover-replication my_group
    If secondary-backend-id is specified (not “default”), it will go to
    the specified backend id:
        cinder group-failover-replication my_group
    --secondary-backend-id <backend_id>
    Expected results: replication_status becomes “failed-over”.

    Run failover replication group again to fail the group back to
    the primary storage:
        cinder group-failover-replication my_group
    --secondary-backend-id default
    Expected results: replication_status becomes “enabled”.

    Disable replication group:
        cinder group-disable-replication my_group
    Expected results: replication_status becomes “disabled”.

    APIImpact
    DocImpact
    Implements: blueprint replication-cg

    Change-Id: I4d488252bd670b3ebabbcc9f5e29e0e4e913765a