a6bce01980
The XML root element of Docbook XML files should match the following format: <ELEMENT xmlns="http://docbook.org/ns/docbook" xmlns:xi="http://www.w3.org/2001/XInclude" xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0" xml:id="THE_XML_ID_OF_THE_ELEMENT"> Change-Id: I02a75b63d0fb3ea4a7d015794b9229a94ddad279
44 lines
2.4 KiB
XML
44 lines
2.4 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<section xmlns="http://docbook.org/ns/docbook"
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xmlns:xi="http://www.w3.org/2001/XInclude"
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xmlns:xlink="http://www.w3.org/1999/xlink"
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version="5.0"
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xml:id="section_conductor">
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<title>Conductor</title>
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<para>The <systemitem class="service">nova-conductor</systemitem>
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service enables OpenStack to function without compute nodes
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accessing the database. Conceptually, it implements a new
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layer on top of <systemitem class="service"
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>nova-compute</systemitem>. It should not be deployed on
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compute nodes, or else the security benefits of removing
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database access from <systemitem class="service"
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>nova-compute</systemitem> are negated. Just like
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other nova services such as <systemitem class="service"
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>nova-api</systemitem> or nova-scheduler, it can be scaled
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horizontally. You can run multiple instances of <systemitem
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class="service">nova-conductor</systemitem> on different
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machines as needed for scaling purposes.</para>
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<para>The methods exposed by <systemitem
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class="service">nova-conductor</systemitem> are relatively
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simple methods used by <systemitem class="service"
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>nova-compute</systemitem> to offload its database
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operations. Places where <systemitem class="service"
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>nova-compute</systemitem> previously performed database
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access are now talking to <systemitem class="service"
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>nova-conductor</systemitem>. However, we have plans in
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the medium to long term to move more and more of what is
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currently in <systemitem class="service"
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>nova-compute</systemitem> up to the <systemitem
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class="service">nova-conductor</systemitem> layer. The
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Compute service will start to look like a less intelligent
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slave service to <systemitem class="service"
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>nova-conductor</systemitem>. The conductor service will
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implement long running complex operations, ensuring forward
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progress and graceful error handling. This will be especially
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beneficial for operations that cross multiple compute nodes,
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such as migrations or resizes.</para>
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<para>To customize the Conductor, use the configuration option settings
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documented in <xref linkend="config_table_nova_conductor"/>.</para>
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</section>
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