0690eb5abd
Change-Id: I39cabc18e40eee968309b63de3d74e3e828645d9 Signed-off-by: Doug Hellmann <doug@doughellmann.com>
36 lines
1.4 KiB
ReStructuredText
36 lines
1.4 KiB
ReStructuredText
=========
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Memcached
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=========
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Most OpenStack services can use Memcached to store ephemeral data such as
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tokens. Although Memcached does not support typical forms of redundancy such
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as clustering, OpenStack services can use almost any number of instances
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by configuring multiple hostnames or IP addresses.
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The Memcached client implements hashing to balance objects among the instances.
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Failure of an instance only impacts a percentage of the objects,
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and the client automatically removes it from the list of instances.
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Installation
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~~~~~~~~~~~~
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To install and configure Memcached, read the
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`official documentation <https://github.com/Memcached/Memcached/wiki#getting-started>`_.
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Memory caching is managed by `oslo.cache
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<http://specs.openstack.org/openstack/oslo-specs/specs/kilo/oslo-cache-using-dogpile.html>`_.
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This ensures consistency across all projects when using multiple Memcached
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servers. The following is an example configuration with three hosts:
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.. code-block:: ini
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Memcached_servers = controller1:11211,controller2:11211,controller3:11211
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By default, ``controller1`` handles the caching service. If the host goes down,
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``controller2`` or ``controller3`` will complete the service.
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For more information about Memcached installation, see the
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*Environment -> Memcached* section in the
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`Installation Tutorials and Guides <https://docs.openstack.org/ocata/install/>`_
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depending on your distribution.
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