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33 lines
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.. _shared_file_systems_scheduling:
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==========
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Scheduling
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==========
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The Shared File Systems service provides unified access for a variety of
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different types of shared file systems. To achieve this, the Shared File
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Systems service uses a scheduler. The scheduler collects information from
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the active shared services and makes decisions such as what shared services
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will be used to create a new share. To manage this process, the Shared
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File Systems service provides Share types API.
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A share type is a list from key-value pairs called extra-specs. Some of them,
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called required and un-scoped extra-specs, the scheduler uses for lookup of
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the shared service suitable for a new share with the specified share type.
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For more information about extra-specs and their type, see `Capabilities
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and Extra-Specs <http://docs.openstack.org/developer/manila/devref/capabilities_and_extra_specs.html>`_ section in developer documentation.
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The general scheduler workflow is described below.
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#. Share services report information about the number of existing pools, their
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capacities and capabilities.
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#. When a request on share creation comes in, the scheduler picks a service
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and pool that fits the need best to serve the request, using share type
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filters and back end capabilities. If back end capabilities pass through,
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all filters request to the selected back end where the target pool resides.
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#. The share driver gets the message and lets the target pool serve the
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request as the scheduler instructs. The scoped and un-scoped share type
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extra-specs are available for the driver implementation to use as needed.
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