libvirt: support for virtozzo storage volume driver

The purpose of this spec is to add a support for volumes hosted
by Virtuozzo storage.

Virtuozzo Storage is a fault-tolerant distributed storage system
optimized for virtualization workloads. From client's point of
view it is a remote file system storage similar to NFS or GlusterFS.

A third-party vzstorage-ci system is running testing jobs on nova
changes.

CI wiki page:
https://wiki.openstack.org/wiki/ThirdPartySystems/Virtuozzo_Storage_CI

blueprint libvirt-vzstorage-volume-support

Previously-approved: Mitaka

Change-Id: Ide2c952c577b36ad1b7f72012336f300f2f3331c

specs/newton/approved/libvirt-vzstorage-volume-support.rst

@@ -0,0 +1,151 @@
+..
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+===================================================================
+Libvirt: Support for attaching volumes located on Virtuozzo Storage
+===================================================================
+
+https://blueprints.launchpad.net/nova/+spec/libvirt-vzstorage-volume-support
+
+The purpose of this blueprint is to add an ability to use volumes hosted by
+Virtuozzo Storage [1]_ previously implemented as one of Cinder Drivers [2]_.
+
+Problem description
+===================
+
+Virtuozzo Storage is a fault-tolerant distributed storage system. From
+client's point of view it is a remote file system storage similar to
+NFS, GlusterFS or CIFS.
+
+Virtuozzo Storage allows to use disk space of conventional linux systems to
+provide fault-tolerant storage with automatic recovery. It's optimized for
+performance of virtualization workloads and has strong data consistency.
+
+Use Cases
+----------
+
+A user is able to attach block storage exported in the form of virtual
+disks resided on Virtuozzo Storage to Nova instances.
+
+Proposed change
+===============
+
+A new volume driver is added in order to support attaching volumes resided on
+Virtuozzo Storage. This volume driver has a similiar workflow to what NFS
+and SMBFS volume drivers have.
+
+The CI system [3]_ runs on Nova tree and checks each Nova patch with
+Virtozzo Storage and leaves a comment about status of tempest run.
+
+Alternatives
+------------
+
+None
+
+Data model impact
+-----------------
+
+None
+
+REST API impact
+---------------
+
+None
+
+Security impact
+---------------
+
+The share credentials will be parsed in the volume connection info and used
+when mounting a Virtuozzo Storage cluster.
+
+Notifications impact
+--------------------
+
+None
+
+Other end user impact
+---------------------
+
+None
+
+Performance Impact
+------------------
+
+None
+
+Other deployer impact
+---------------------
+
+The deployer will be able to configure the path where the Virtuoozo Storage
+clusters  will be mounted, as well as setting mount flags.
+
+Developer impact
+----------------
+
+None
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  eantyshev
+
+Other contributors:
+  mnestratov, dguryanov
+
+
+Work Items
+----------
+
+Spec approval.
+Implementation: [4]_
+Documentaiton.
+
+Dependencies
+============
+
+Remotefs os-brick part merged in review [5]_
+Cinder part implementation merged in review [6]_
+
+
+Testing
+=======
+
+This feature should be tested in conjunction with the Virtuozzo Storage
+Cinder Volume driver. The existing Tempest tests along with the related unit
+tests should be enough.
+
+A third party CI testing system is up and running [3]_
+
+Documentation Impact
+====================
+
+Using the Virtuozzo Storage backend should be documented.
+
+References
+==========
+.. [1] https://virtuozzo.com/wp-content/uploads/2016/03/Virtuozzo_Virtuozzo_Storage_DS_A4_EN_20160305.pdf
+.. [2] https://blueprints.launchpad.net/cinder/+spec/virtuozzo-cloud-storage-support
+.. [3] https://wiki.openstack.org/wiki/ThirdPartySystems/Virtuozzo_Storage_CI
+.. [4] https://review.openstack.org/#/c/190843/
+.. [5] https://review.openstack.org/#/c/188805/
+.. [6] https://review.openstack.org/#/c/188869/
+
+History
+=======
+
+.. list-table:: Revisions
+   :header-rows: 1
+
+   * - Release Name
+     - Description
+   * - Mitaka
+     - Approved.
+   * - Newton
+     - Re-introduced.