Clean up user_requirements_hybrid.xml

- Edited to improve writing generally
- Removed duplicated legal content which was added to a common section.
  See https://review.openstack.org/#/c/212299/

Change-Id: Ib7e7957dc1c9516902234b56b73ce604a9650467
Implements: blueprint arch-guide
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Brian Moss 2015-08-14 10:23:08 +10:00
parent 79d32c6607
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<?dbhtml stop-chunking?>
<title>User requirements</title>
<para>Hybrid cloud architectures are complex, especially those
that use heterogeneous cloud platforms. It is important to
make sure that design choices match requirements in such a way that
the benefits outweigh the inherent additional complexity and risks.</para>
<para>Business considerations when designing a hybrid
cloud deployment include:</para>
that use heterogeneous cloud platforms. Ensure that design choices
match requirements so that the benefits outweigh the inherent additional
complexity and risks.</para>
<variablelist>
<title>Business considerations when designing a hybrid
cloud deployment</title>
<varlistentry>
<term>Cost</term>
<listitem>
@ -30,22 +30,20 @@
<varlistentry>
<term>Revenue opportunity</term>
<listitem>
<para>Revenue opportunities vary
greatly based on the intent and use case of the cloud.
As a commercial, customer-facing product, you must consider
whether building over multiple platforms makes the
design more attractive to customers.</para>
<para>Revenue opportunities vary based on the intent and use case
of the cloud. As a commercial, customer-facing product, you
must consider whether building over multiple platforms makes
the design more attractive to customers.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Time-to-market</term>
<listitem>
<para>One of the most common reasons to
use cloud platforms is to improve the time-to-market of
a new product or application. For example, using multiple
cloud platforms is viable because there is an existing
investment in several applications. It is faster to tie
the investments together rather than migrate the
<para>One common reason to use cloud platforms is to improve the
time-to-market of a new product or application. For example,
using multiple cloud platforms is viable because there is an
existing investment in several applications. It is faster to
tie the investments together rather than migrate the
components and refactoring them to a single platform.</para>
</listitem>
</varlistentry>
@ -69,83 +67,44 @@
</varlistentry>
</variablelist>
<section xml:id="legal-requirements-hybrid">
<title>Legal requirements</title>
<para>Many jurisdictions have legislative and regulatory
requirements governing the storage and management of data in
cloud environments. Common areas of regulation include:</para>
<itemizedlist>
<listitem>
<para>Data retention policies ensuring storage of
persistent data and records management to meet data
archival requirements.</para>
</listitem>
<listitem>
<para>Data ownership policies governing the possession and
responsibility for data.</para>
</listitem>
<listitem>
<para>Data sovereignty policies governing the storage of
data in foreign countries or otherwise separate
jurisdictions.</para>
</listitem>
<listitem>
<para>Data compliance policies governing certain types of
information needs to reside in certain locations due
to regular issues and, more importantly, cannot reside
in other locations for the same reason.</para>
</listitem>
</itemizedlist>
<para>Examples of such legal frameworks include the data
protection framework of the European Union (<link
xlink:href="http://ec.europa.eu/justice/data-protection/">Reform of data protection legislation</link>)
and the requirements of the Financial Industry Regulatory
Authority (<link
xlink:href="http://www.finra.org/Industry/Regulation/FINRARules/">FINRA Rules</link>)
in the United States. Consult a local regulatory body for more
information.</para>
</section>
<section xml:id="workload-considerations">
<title>Workload considerations</title>
<para>A workload can be a single application or a suite of applications that
work together. It can also be a duplicate set of applications that need to
run on multiple cloud environments. In a hybrid cloud
deployment, the same workload often needs to function
equally well on radically different public and private cloud
environments. The architecture needs to address these
potential conflicts, complexity, and platform
incompatibilities. Some possible use cases for a hybrid cloud architecture
include:</para>
<para>A workload can be a single application or a suite of applications
that work together. It can also be a duplicate set of applications that
need to run on multiple cloud environments. In a hybrid cloud
deployment, the same workload often needs to function
equally well on radically different public and private cloud
environments. The architecture needs to address these
potential conflicts, complexity, and platform
incompatibilities.</para>
<variablelist>
<title>Use cases for a hybrid cloud architecture</title>
<varlistentry>
<term>Dynamic resource expansion or <literal>"bursting"</literal></term>
<term>Dynamic resource expansion or bursting</term>
<listitem>
<para>An application that requires additional resources is another
common reason you might use a multiple cloud architecture.
<para>An application that requires additional resources may suit
a multiple cloud architecture.
For example, a retailer needs additional resources
during the holiday retail season, but does not want to build expensive
cloud resources to meet the peak demand. The user might
have an OpenStack private cloud but want to burst to
AWS or some other public cloud for these peak load
during the holiday season, but does not want to add private
cloud resources to meet the peak demand. The user can
accommodate the increased load by bursting to
a public cloud for these peak load
periods. These bursts could be for long or short
cycles ranging from hourly to yearly.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Disaster recovery-business continuity</term>
<term>Disaster recovery and business continuity</term>
<listitem>
<para>The cheaper storage and instance management makes a good case for
using the cloud as a secondary site. Using OpenStack public
or private cloud in combination with the public cloud for
these purposes is popular.</para>
<para>Cheaper storage makes the public
cloud suitable for maintaining backup applications.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Federated hypervisor-instance management</term>
<term>Federated hypervisor and instance management</term>
<listitem>
<para>Adding self-service, charge back and transparent delivery of
the right resources from a federated pool can be cost
<para>Adding self-service, charge back, and transparent delivery of
the resources from a federated pool can be cost
effective. In a hybrid cloud environment, this is a
particularly important consideration. Look for a cloud
that provides cross-platform hypervisor support and
@ -155,85 +114,59 @@
<varlistentry>
<term>Application portfolio integration</term>
<listitem>
<para>An enterprise cloud delivers efficient application portfolio management
and deployments by leveraging
self-service features and rules for deployments based
on types of use. Stitching together multiple existing
cloud environments that are already in production or development
is a common driver when building hybrid cloud architectures.</para>
<para>An enterprise cloud delivers efficient application portfolio
management and deployments by leveraging
self-service features and rules according to use. Integrating
existing cloud environments is a common driver when building
hybrid cloud architectures.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Migration scenarios</term>
<listitem>
<para>A common reason to create a
hybrid cloud architecture is to allow the migration of
applications between different clouds. Permanent migration of the
application to a new platform is one reason, or another might be
because the application requires support on multiple
platforms.</para>
<para>Hybrid cloud architecture enables the migration of
applications between different clouds.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>High availability</term>
<listitem>
<para>Another important reason for
wanting a multiple cloud architecture is to address
the needs for high availability. Using a
combination of multiple locations and platforms, a
design can achieve a level of availability that is not
possible with a single platform. This approach does
add a significant amount of complexity.</para>
<para>A combination of locations and platforms enables a
level of availability that is not
possible with a single platform. This approach increases
design complexity.</para>
</listitem>
</varlistentry>
</variablelist>
<para>In addition to thinking about how the workload works on
a single cloud, the design must accommodate the added
complexity of needing the workload to run on multiple cloud
platforms. We recommend exploring the complexity of transferring
<para>As running a workload on multiple cloud platforms increases design
complexity, we recommend first exploring options such as transferring
workloads across clouds at the application, instance, cloud platform,
hypervisor, and network levels.</para>
</section>
<section xml:id="tools-considerations-hybrid">
<title>Tools considerations</title>
<para>When working with designs spanning multiple clouds, the
design must incorporate tools to facilitate working across
those multiple clouds. Some of the user requirements drive the
need for tools that perform the following functions:</para>
<para>Hybrid cloud designs must incorporate tools to facilitate working
across multiple clouds.</para>
<variablelist>
<title>Tool functions</title>
<varlistentry>
<term>Broker between clouds</term>
<listitem>
<para>Since the multiple cloud
architecture assumes that there are at least two
different and possibly incompatible platforms that are
likely to have different costs, brokering software
evaluates relative costs between different
cloud platforms. The name for these solutions is
Cloud Management Platforms (CMPs).
Examples include Rightscale, Gravitent, Scalr,
CloudForms, and ManageIQ. These tools allow the
designer to determine the right location for the
<para>Brokering software evaluates relative costs between different
cloud platforms. Cloud Management Platforms (CMP)
allow the designer to determine the right location for the
workload based on predetermined criteria.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Facilitate orchestration across the clouds</term>
<listitem>
<para>CMPs are tools are used to tie everything together. Using
cloud orchestration tools improves the management
of IT application portfolios as they migrate onto
<para>CMPs simplify the migration of application workloads between
public, private, and hybrid cloud platforms. We recommend
using cloud orchestration tools for managing a diverse
portfolio of installed systems across multiple cloud
platforms. The typical enterprise IT application
portfolio is still comprised of a few thousand
applications scattered over legacy hardware,
virtualized infrastructure, and now dozens of
disjointed shadow public Infrastructure-as-a-Service
(IaaS) and Software-as-a-Service (SaaS) providers and
offerings.</para>
portfolio of systems and applications across multiple cloud
platforms.</para>
</listitem>
</varlistentry>
</variablelist>
@ -241,16 +174,15 @@
<section xml:id="network-considerations-hybrid">
<title>Network considerations</title>
<para>The network services functionality is an important factor to
assess when choosing a CMP and cloud provider. Considerations
are functionality, security, scalability and HA. Important tasks for
the architecture include the verification and ongoing testing of
critical features for the cloud endpoint.</para>
<para>It is important to consider the functionality, security, scalability,
availability, and testability of network when choosing a CMP and cloud
provider.</para>
<itemizedlist>
<listitem>
<para>Decide on a network functionality framework and
design a minimum functionality test. This ensures
testing and functionality persists during and after upgrades.</para>
<para>Decide on a network framework and
design minimum functionality tests. This ensures
testing and functionality persists during and after
upgrades.</para>
</listitem>
<listitem>
<para>Scalability across multiple cloud providers may
@ -263,15 +195,15 @@
<listitem>
<para>High availability implementations vary in
functionality and design. Examples of some common
methods are active-hot-standby, active-passive and
active-active. Development of high availability and test frameworks
is necessary to insure understanding of functionality
and limitations.</para>
methods are active-hot-standby, active-passive, and
active-active. Development of high availability and test
frameworks is necessary to insure understanding of
functionality and limitations.</para>
</listitem>
<listitem>
<para>Consider the security of data between
the client, the endpoint, and any traffic that traverses the
multiple clouds.</para>
<para>Consider the security of data between the client and the
endpoint, and of traffic that traverses the multiple
clouds.</para>
</listitem>
</itemizedlist>
</section>
@ -279,68 +211,46 @@
<section xml:id="risk-mitigation-management-hybrid">
<title>Risk mitigation and management considerations</title>
<para>Hybrid cloud architectures introduce additional risk because
they add additional complexity and potentially conflicting or
they are more complex than a single cloud design and may involve
incompatible components or tools. However, they also reduce
risk by spreading workloads over multiple providers. This
means, if one was to go out of business, the organization
could remain operational. Heightened risks when using a hybrid
cloud architecture include:</para>
risk by spreading workloads over multiple providers.</para>
<variablelist>
<title>Hybrid cloud risks</title>
<varlistentry>
<term>Provider availability or implementation details</term>
<listitem>
<para>
This can range from the company going out of business
to the company changing how it delivers its services.
The design of a cloud architecture is meant to be
flexible and changeable; however, the cloud is
perceived to be both rock solid and ever flexible at
the same time.</para>
Business changes can affect provider availability. Likewise,
changes in a provider's service can disrupt a hybrid cloud
environment or increase costs.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Differing SLAs</term>
<listitem>
<para>Users of hybrid cloud environments
potentially encounter some losses through differences
in service level agreements. A hybrid cloud design
needs to accommodate the different SLAs the various clouds
involved in the design offer, and must
address the actual enforceability of the providers'
SLAs.</para>
<para>Hybrid cloud designs must accommodate differences in SLAs
between providers, and consider their enforceability.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Security levels</term>
<listitem>
<para>Securing multiple cloud
environments is more complex than securing a single
cloud environment. We recommend addressing concerns at
environments is more complex than securing single
cloud environments. We recommend addressing concerns at
the application, network, and cloud platform levels.
One issue is that different
cloud platforms approach security differently, and a
hybrid cloud design must address and compensate for
differences in security approaches. For example, AWS
uses a relatively simple model that relies on user
privilege combined with firewalls.</para>
Be aware that each cloud platform approaches security
differently, and a hybrid cloud design must address and
compensate for these differences.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Provider API changes</term>
<listitem>
<para>APIs are crucial in a hybrid
cloud environment. As a consumer of a provider's cloud
services, an organization rarely has control
over provider changes to APIs. Cloud services that
might have previously had compatible APIs may no
longer work. This is particularly a problem with AWS
and OpenStack AWS-compatible APIs. The planning of OpenStack
included the maintenance of compatibility with changes in AWS
APIs. However, over time, the APIs have
become more divergent in functionality. One way to
address this issue is to focus on using only the most
common and basic APIs to minimize potential
conflicts.</para>
<para>Consumers of external clouds rarely have control over
provider changes to APIs, and changes can break compatibility.
Using only the most common and basic APIs can minimize
potential conflicts.</para>
</listitem>
</varlistentry>
</variablelist>