06708191d6
This commit does the following: - sets all shell prompts in code-blocks to the root prompt - uses shell-session code-block since the shell prompt was being treated as a comment - links configure-aodh.rst in configure.rst (running tox was complaining that this file wasn't being linked anywhere) - other minor cleanup Change-Id: I9e3ac8bb0cabd1cc17952cfd765dbb0d8f7b6fa2
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`Home <index.html>`_ OpenStack-Ansible Installation Guide
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Storage Policies
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----------------
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Storage Policies allow segmenting the cluster for various purposes
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through the creation of multiple object rings. Using policies, different
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devices can belong to different rings with varying levels of
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replication. By supporting multiple object rings, Object Storage can
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segregate the objects within a single cluster.
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Storage policies can be used for the following situations:
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- Differing levels of replication: A provider may want to offer 2x
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replication and 3x replication, but does not want to maintain two
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separate clusters. They can set up a 2x policy and a 3x policy and
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assign the nodes to their respective rings.
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- Improving performance: Just as solid state drives (SSD) can be used
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as the exclusive members of an account or database ring, an SSD-only
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object ring can be created to implement a low-latency or high
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performance policy.
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- Collecting nodes into groups: Different object rings can have
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different physical servers so that objects in specific storage
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policies are always placed in a specific data center or geography.
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- Differing storage implementations: A policy can be used to direct
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traffic to collected nodes that use a different disk file (for
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example, Kinetic, GlusterFS).
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Most storage clusters do not require more than one storage policy. The
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following problems can occur if using multiple storage policies per
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cluster:
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- Creating a second storage policy without any specified drives (all
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drives are part of only the account, container, and default storage
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policy groups) creates an empty ring for that storage policy.
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- A non-default storage policy is used only if specified when creating
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a container, using the ``X-Storage-Policy: <policy-name>`` header.
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After the container is created, it uses the created storage policy.
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Other containers continue using the default or another storage policy
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specified when created.
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For more information about storage policies, see: `Storage
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Policies <http://docs.openstack.org/developer/swift/overview_policies.html>`_
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--------------
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.. include:: navigation.txt
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