manila/doc/source/glossary.rst

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 python-manilaclient to interact with the API.

python-manilaclient

Command line interface to interact with manila via manila-api and also a Python module to interact programmatically with manila.

manila-scheduler

Responsible for scheduling/routing requests to the appropriate 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 manila-scheduler. The value of this capability can be one of readable, writable or dr.

readable

A type of replication supported by manila in which there is one 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 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 manila in which there is one 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 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 manila. If the value is 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 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 active replica and the share replica.

replication_change

State of a non-active replica when it is being promoted to become the 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 manila.