openstack-manuals/doc/arch-design/ch_massively_scalable.xml

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<title>Massively scalable</title>
<para>A massively scalable architecture is a cloud
implementation that is either a very large deployment, such as
a commercial service provider might build, or
one that has the capability to support user requests for large
amounts of cloud resources.</para>
<para>An example is an infrastructure in which requests to service
500 or more instances at a time is common. A massively scalable
infrastructure fulfills such a request without exhausting the
available cloud infrastructure resources. While the high capital
cost of implementing such a cloud architecture means that it
is currently in limited use, many organizations are planning
for massive scalability in the future.</para>
<para>A massively scalable OpenStack cloud design presents a
unique set of challenges and considerations. For the most part
it is similar to a general purpose cloud architecture, as it
is built to address a non-specific range of potential use
cases or functions. Typically, it is rare that particular
workloads determine the design or configuration of massively
scalable clouds. The massively scalable cloud is most often
built as a platform for a variety of workloads. Because private
organizations rarely require or have the resources for them,
massively scalable OpenStack clouds are generally built as
commercial, public cloud offerings.</para>
<para>Services provided by a massively scalable OpenStack cloud
include:</para>
<itemizedlist>
<listitem>
<para>Virtual-machine disk image library</para>
</listitem>
<listitem>
<para>Raw block storage</para>
</listitem>
<listitem>
<para>File or object storage</para>
</listitem>
<listitem>
<para>Firewall functionality</para>
</listitem>
<listitem>
<para>Load balancing functionality</para>
</listitem>
<listitem>
<para>Private (non-routable) and public (floating) IP
addresses</para>
</listitem>
<listitem>
<para>Virtualized network topologies</para>
</listitem>
<listitem>
<para>Software bundles</para>
</listitem>
<listitem>
<para>Virtual compute resources</para>
</listitem>
</itemizedlist>
<para>Like a general purpose cloud, the instances deployed in a
massively scalable OpenStack cloud do not necessarily use
any specific aspect of the cloud offering (compute, network,
or storage). As the cloud grows in scale, the number of
workloads can cause stress on all the cloud
components. This adds further stresses to supporting
infrastructure such as databases and message brokers. The
architecture design for such a cloud must account for these
performance pressures without negatively impacting user
experience.</para>
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<xi:include href="massively_scalable/section_tech_considerations_massively_scalable.xml"/>
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