589069caff
Add new entries: north-south traffic, east-west traffic and TripleO. Add entries for these terms to the Arch Design Guide. Use consistent spelling for these entries. Include some edits for improved wording. Change-Id: Ic241664a44c0e41e3961206b626eef2acb0c5b31
86 lines
4.0 KiB
XML
86 lines
4.0 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE section [
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<!ENTITY % openstack SYSTEM "../../common/entities/openstack.ent">
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%openstack;
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]>
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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="arch-guide-openstack-on-openstack">
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<?dbhtml stop-chunking?>
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<title>OpenStack on OpenStack</title>
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<para>In some cases it is necessary to run OpenStack nested on top
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of another OpenStack cloud. This scenario allows for complete
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OpenStack cloud environments to be managed and provisioned on
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instances running on hypervisors and servers controlled by the
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underlying OpenStack cloud. Public cloud providers can use
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this technique to effectively manage the upgrade and
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maintenance process on complete OpenStack-based clouds.
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Developers and those testing OpenStack can also use the
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guidance to provision their own OpenStack environments on
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available OpenStack Compute resources, whether public or
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private.</para>
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<section xml:id="challenges-for-nested-cloud">
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<title>Challenges</title>
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<para>The network aspect of deploying a nested cloud is the most
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complicated aspect of this architecture. When using VLANs,
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these will need to be exposed to the physical ports on which
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the undercloud runs, as the bare metal cloud owns all the
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hardware, but they also need to be exposed to the nested
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levels as well. Alternatively, network overlay technologies
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can be used on the overcloud (the OpenStack cloud running on
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OpenStack) to provide the required software defined networking
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for the deployment.</para>
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</section>
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<section xml:id="hypervisor-nested-cloud">
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<title>Hypervisor</title>
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<para>A key question to address in this scenario is the decision
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about which approach should be taken to provide a nested
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hypervisor in OpenStack. This decision influences which
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operating systems can be used for the deployment of the nested
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OpenStack deployments.</para>
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</section>
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<section xml:id="possible-solutions-nested-cloud-deployment">
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<title>Possible solutions: deployment</title>
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<para>Deployment of a full stack can be challenging but this
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difficulty can be readily be mitigated by creating a Heat
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template to deploy the entire stack or a configuration
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management system. Once the Heat template is created,
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deploying additional stacks will be a trivial thing and can be
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performed in an automated fashion.</para>
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<para>The OpenStack-on-OpenStack project (<glossterm>TripleO</glossterm>)
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addresses this issue—currently, however, the project does
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not completely cover nested stacks. For more information, see
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<link
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xlink:href="https://wiki.openstack.org/wiki/TripleO">
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https://wiki.openstack.org/wiki/TripleO</link>.
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</para>
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</section>
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<section xml:id="possible-solutions-nested-cloud-hypervisor">
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<title>Possible solutions: hypervisor</title>
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<para>In the case of running TripleO, the underlying OpenStack
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cloud deploys the Compute nodes as bare-metal. OpenStack would
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then be deployed on these Compute bare-metal servers with the
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appropriate hypervisor, such as KVM.</para>
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<para>In the case of running smaller OpenStack clouds for testing
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purposes, and performance would not be a critical factor, QEMU
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can be utilized instead. It is also possible to run a KVM
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hypervisor in an instance
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(see <link xlink:href="http://davejingtian.org/2014/03/30/nested-kvm-just-for-fun/">
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http://davejingtian.org/2014/03/30/nested-kvm-just-for-fun/</link>),
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though this is not a supported configuration, and could be a
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complex solution for such a use case.</para>
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</section>
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<section xml:id="nested-cloud-diagram">
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<title>Diagram</title>
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<para>
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<mediaobject>
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<imageobject>
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<imagedata contentwidth="4in" fileref="../images/Specialized_OOO.png"/>
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</imageobject>
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</mediaobject>
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</para>
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</section>
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</section>
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