manila/doc/source/reference/glossary.rst
Tom Barron 90060722a9 doc migration: new directory layout
This patch introduces a new directory layout
in doc/source in conformance with the OpenStack
manuals project migration spec [1], moves the
existing content in manila/doc/source into the
new directories, and adjusts index files accordingly.

This is the first step in the migration process
as outlined in the spec.

[1] https://specs.openstack.org/openstack/docs-specs/specs/pike/os-manuals-migration.html

Partial-Bug: #1706181
Needed-By: I7924d94b82e7c8d9716bad7a219fc38c57970773
Depends-On: Ifc80fc56648cef74c85464321d1850e8c68449a0
Depends-On: Ia750cb049c0f53a234ea70ce1f2bbbb7a2aa9454
Change-Id: Ieea33262101a1d2459492c1c8aaac5fe042279f6
2017-08-24 09:16:25 -04:00

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========
Glossary
========
.. glossary::
manila
OpenStack project to provide "Shared Filesystems as a service".
manila-api
Service that provides a stable RESTful API.
The service authenticates and routes requests throughout the Shared Filesystem service.
There is :term:`python-manilaclient` to interact with the API.
python-manilaclient
Command line interface to interact with :term:`manila` via :term:`manila-api` and also a
Python module to interact programmatically with :term:`manila`.
manila-scheduler
Responsible for scheduling/routing requests to the appropriate :term:`manila-share` service.
It does that by picking one back-end while filtering all except one back-end.
manila-share
Responsible for managing Shared File Service devices, specifically the back-end devices.
DHSS
Acronym for 'driver handles share servers'. It defines two different share driver modes
when they either do handle share servers or not. Each driver is allowed to work only in
one mode at once. Requirement is to support, at least, one mode.
replication_type
Type of replication supported by a share driver. If the share driver supports replication
it will report a valid value to the :term:`manila-scheduler`. The value of this
capability can be one of :term:`readable`, :term:`writable` or :term:`dr`.
readable
A type of replication supported by :term:`manila` in which there is one :term:`active`
replica (also referred to as `primary` share) and one or more non-active replicas (also
referred to as `secondary` shares). All share replicas have at least one export location
and are mountable. However, the non-active replicas cannot be written to until after
promotion.
writable
A type of replication supported by :term:`manila` in which all share replicas are
writable. There is no requirement of a promotion since replication is synchronous.
All share replicas have one or more export locations each and are mountable.
dr
Acronym for `Disaster Recovery`. It is a type of replication supported by :term:`manila`
in which there is one :term:`active` replica (also referred to as `primary` share) and
one or more non-active replicas (also referred to as `secondary` shares). Only the
`active` replica has one or more export locations and can be mounted. The non-active
replicas are inaccessible until after promotion.
active
In :term:`manila`, an `active` replica refers to a share that can be written to. In
`readable` and `dr` styles of replication, there is only one `active` replica at any given
point in time. Thus, it may also be referred to as the `primary` share. In `writable`
style of replication, all replicas are writable and there may be no distinction of a
`primary` share.
replica_state
An attribute of the Share Instance (Share Replica) model in :term:`manila`. If the value is
:term:`active`, it refers to the type of the replica. If the value is one of `in_sync` or
`out_of_sync`, it refers to the state of consistency of data between the :term:`active`
replica and the share replica. If the value is `error`, a potentially irrecoverable
error may have occurred during the update of data between the :term:`active` replica and
the share replica.
replication_change
State of a non-active replica when it is being promoted to become the :term:`active`
replica.
recovery point objective
Abbreviated as ``RPO``, recovery point objective is a target window of time between which
a storage backend may guarantee that data is consistent between a primary and a secondary
replica. This window is **not** managed by :term:`manila`.