[ha-guide] Proposal to improve the HA guide for Ocata/Pike

Change-Id: I41c52816aba1eb8f65c289fa30a7ded904a9bb84

specs/ocata/improve-ha-guide.rst

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+===================================
+Improve the High Availability Guide
+===================================
+
+https://blueprints.launchpad.net/openstack-manuals/+spec/implement-ha-guide-todos
+
+Problem description
+===================
+
+Presently, the High Availability (HA) Guide is incomplete. Information is
+sparse and there are sections that have simply not been filled in.
+
+The current guide is also out of date with regards to current best practices,
+and it contains unnecessary information that should be removed.
+
+Proposed change
+===============
+
+Firstly, reach consensus on the intended audience and high-level use cases
+for the guide:
+
+* As a cloud deployer, I need an OpenStack HA guide so that I can understand
+  both the architectural principles behind building an HA OpenStack cloud,
+  and the concrete steps involved in an implementation.
+
+* As a cloud operator, I need an OpenStack HA guide so that I can understand
+  how an existing HA OpenStack cloud works and what is required for its
+  maintenance.
+
+Based on that consensus, this spec proposes that the HA guide aims to define,
+justify, and explain a high level architecture for a highly available setup
+which uses the Pacemaker cluster manager to provide:
+
+    * Detection and recovery of machine and application-level failures
+    * Startup/shutdown ordering between applications
+    * Preferences for other applications that must/must-not run on the same
+      machine
+    * Provably correct response to any failure or cluster state
+
+The guide will aim to stay relevant across all distributions whilst not
+attempting to give every tiny detail about how to implement HA for each
+distribution. It will also aim to avoid duplicating too much
+information which can be found elsewhere. For example, basic package
+installation for a given distribution.
+
+Since the existing guide already has plenty of helpful and relevant
+information, the proposal for this guide aims to avoid any rip-and-replace
+action preferring instead incremental change.
+
+Andrew Beekhof (specialty team lead) proposes to use the following document
+as a reference providing updated information for the improved guide:
+https://github.com/beekhof/osp-ha-deploy/blob/master/ha-openstack.md
+
+    .. note::
+
+       The above Github document contains heavy Red Hat content. Some may be
+       included in the final publication of the HA guide however it will be
+       structured such that advocates of other distributions/tools will be
+       able to easily add alternatives.
+
+Alternatives
+------------
+
+* Leave the guide as is, and have the community slowly work at it over
+  time.
+
+* Retire the guide, move relevant information to other guides and archive
+  it appropriately.
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+* Andrew Beekhof - beekhof
+* Adam Spiers - aspiers
+* Alexandra Settle - asettle
+
+Work Items
+----------
+#. Go through HA guide bug list (see reference item 2) and remove what it out
+   of date, and deal with any bugs that are relevant and current.
+
+#. Go through HA guide and delete outdated or irrelevant information.
+
+#. Rearchitect the guide for new structure.
+
+#. Introduce new content based on the above Github document, and SME content.
+
+Dependencies
+============
+
+* Potentially dependent on community engagement and SMEs providing content.
+
+Testing
+=======
+
+This document will be tested by the community as it is updated.
+
+References
+==========
+
+#. Mailing list discussion, December 2016: http://lists.openstack.org/pipermail/openstack-docs/2016-December/009410.html
+
+#. Growing list of relevant bugs: https://bugs.launchpad.net/openstack-manuals/+bugs?field.tag=ha-guide