0043fb7a7c
Many minor edits: Improve markup, follow conventions, add glossary items, fix capitalization,... Change-Id: I85693ef2d2c617327c707d13ffd5f05b4d97d1d7
213 lines
10 KiB
XML
213 lines
10 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="user-requirements-general-purpose">
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<?dbhtml stop-chunking?>
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<title>User requirements</title>
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<para>The general purpose cloud is built following the
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<glossterm baseform="IaaS">Infrastructure-as-a-Service (IaaS)</glossterm>
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model; as a platform best
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suited for use cases with simple requirements. The general
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purpose cloud user requirements themselves are typically not
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complex. However, it is still important to capture them even
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if the project has minimum business and technical requirements
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such as a proof of concept (PoC) or a small lab
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platform.</para>
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<para>These user considerations are written from the perspective
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of the organization that is building the cloud, not from the
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perspective of the end-users who will consume cloud services
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provided by this design.
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</para>
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<variablelist>
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<varlistentry>
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<term>Cost</term>
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<listitem>
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<para>Financial factors are a primary concern for
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any organization. Since general purpose clouds are
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considered the baseline from which all other cloud
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architecture environments derive, cost will commonly
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be an important criteria. This type of cloud, however,
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does not always provide the most cost-effective
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environment for a specialized application or
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situation. Unless razor-thin margins and costs have
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been mandated as a critical factor, cost should not be
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the sole consideration when choosing or designing a
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general purpose architecture.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Time to market</term>
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<listitem>
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<para>Another common business factor in
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building a general purpose cloud is the ability to
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deliver a service or product more quickly and
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flexibly. In the modern hyper-fast business world,
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being able to deliver a product in six months instead
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of two years is often a major driving force behind the
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decision to build a general purpose cloud. General
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purpose clouds allow users to self-provision and gain
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access to compute, network, and storage resources
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on-demand thus decreasing time to market. It may
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potentially make more sense to build a general purpose
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PoC as opposed to waiting to finalize the ultimate use
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case for the system. The tradeoff with taking this
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approach is the risk that the general purpose cloud is
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not optimized for the actual final workloads. The
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final decision on which approach to take will be
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dependent on the specifics of the business objectives
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and time frame for the project.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Revenue opportunity</term>
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<listitem>
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<para>The revenue opportunity for a
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given cloud will vary greatly based on the intended
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use case of that particular cloud. Some general
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purpose clouds are built for commercial customer
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facing products, but there are plenty of other reasons
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that might make the general purpose cloud the right
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choice. A small cloud service provider (CSP) might
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want to build a general purpose cloud rather than a
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massively scalable cloud because they do not have the
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deep financial resources needed, or because they do
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not or will not know in advance the purposes for which
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their customers are going to use the cloud. For some
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users, the advantages cloud itself offers mean an
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enhancement of revenue opportunity. For others, the
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fact that a general purpose cloud provides only
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baseline functionality will be a disincentive for use,
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leading to a potential stagnation of potential revenue
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opportunities.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<section xml:id="legal-requirements-general-purpose">
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<title>Legal requirements</title>
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<para>Many jurisdictions have legislative and regulatory
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requirements governing the storage and management of data in
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cloud environments. Common areas of regulation include:</para>
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<itemizedlist>
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<listitem>
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<para>Data retention policies ensuring storage of
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persistent data and records management to meet data
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archival requirements.</para>
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</listitem>
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<listitem>
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<para>Data ownership policies governing the possession and
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responsibility for data.</para>
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</listitem>
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<listitem>
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<para>Data sovereignty policies governing the storage of
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data in foreign countries or otherwise separate
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jurisdictions.</para>
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</listitem>
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<listitem>
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<para>Data compliance policies governing certain types of
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information need to reside in certain locations due to
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regular issues - and more important cannot reside in
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other locations for the same reason.</para>
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</listitem>
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</itemizedlist>
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<para>
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Examples of such legal frameworks include the <link
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xlink:href="http://ec.europa.eu/justice/data-protection/">data
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protection framework</link> of the European Union and the
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requirements of the <link
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xlink:href="http://www.finra.org/Industry/Regulation/FINRARules/">Financial
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Industry Regulatory Authority</link> in the United
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States. Consult a local regulatory body for more information.
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</para>
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</section>
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<section xml:id="technical-requirements">
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<title>Technical requirements</title>
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<para>Technical cloud architecture requirements should be weighted
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against the business requirements.
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</para>
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<variablelist>
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<varlistentry>
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<term>Performance</term>
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<listitem>
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<para>As a baseline product, general purpose
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clouds do not provide optimized performance for any
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particular function. While a general purpose cloud
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should provide enough performance to satisfy average
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user considerations, performance is not a general
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purpose cloud customer driver.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>No predefined usage model</term>
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<listitem>
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<para>The lack of a pre-defined
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usage model enables the user to run a wide variety of
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applications without having to know the application
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requirements in advance. This provides a degree of
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independence and flexibility that no other cloud
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scenarios are able to provide.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>On-demand and self-service application</term>
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<listitem>
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<para>By
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definition, a cloud provides end users with the
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ability to self-provision computing power, storage,
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networks, and software in a simple and flexible way.
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The user must be able to scale their resources up to a
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substantial level without disrupting the underlying
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host operations. One of the benefits of using a
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general purpose cloud architecture is the ability to
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start with limited resources and increase them over
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time as the user demand grows.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Public cloud</term>
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<listitem>
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<para>For a company interested in building a
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commercial public cloud offering based on OpenStack,
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the general purpose architecture model might be the
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best choice because the designers are not going to
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know the purposes or workloads for which the end users
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will use the cloud.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Internal consumption (private) cloud</term>
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<listitem>
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<para>Organizations
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need to determine if it makes the most sense to create
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their own clouds internally. The main advantage of a
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private cloud is that it allows the organization to
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maintain complete control over all the architecture
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and the cloud components. One caution is to think
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about the possibility that users will want to combine
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using the internal cloud with access to an external
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cloud. If that case is likely, it might be worth
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exploring the possibility of taking a multi-cloud
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approach with regard to at least some of the
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architectural elements. Designs that incorporate the
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use of multiple clouds, such as a private cloud and a
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public cloud offering, are described in the
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"Multi-Cloud" scenario, see <xref linkend="multi_site"/>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Security</term>
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<listitem>
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<para>Security should be implemented according
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to asset, threat, and vulnerability risk assessment
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matrices. For cloud domains that require increased
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computer security, network security, or information
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security, general purpose cloud is not considered an
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appropriate choice.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</section>
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</section>
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