User requirements
When building a general purpose cloud, you should follow the
Infrastructure-as-a-Service (IaaS)
model; a platform best suited for use cases with simple requirements.
General purpose cloud user requirements are not complex.
However, it is important to capture them even
if the project has minimum business and technical requirements, such as a
proof of concept (PoC), or a small lab platform.
The following user considerations are written from the perspective of
the cloud builder, not from the perspective of the end user.
Cost
Financial factors are a primary concern for
any organization. Cost is an important criterion
as general purpose clouds are considered the baseline
from which all other cloud architecture environments
derive. General purpose clouds do not always provide
the most cost-effective environment for specialized
applications or situations. Unless razor-thin margins and costs have
been mandated as a critical factor, cost should not be
the sole consideration when choosing or designing a
general purpose architecture.
Time to market
The ability to deliver services or products within
a flexible time frame is a common business factor
when building a general purpose cloud. In today's high-speed business world,
the ability to deliver a product in six months instead
of two years is a driving force behind the
decision to build general purpose clouds. General
purpose clouds allow users to self-provision and gain
access to compute, network, and storage resources
on-demand thus decreasing time to market.
Revenue opportunity
Revenue opportunities for a
cloud will vary greatly based on the intended
use case of that particular cloud. Some general
purpose clouds are built for commercial customer
facing products, but there are alternatives
that might make the general purpose cloud the right
choice. For example, a small cloud service provider (CSP) might
want to build a general purpose cloud rather than a
massively scalable cloud because they do not have the
deep financial resources needed, or because they do
not, or will not, know in advance the purposes for which
their customers are going to use the cloud. For some
users, the advantages cloud itself offers mean an
enhancement of revenue opportunity. For others, the
fact that a general purpose cloud provides only
baseline functionality will be a disincentive for use,
leading to a potential stagnation of potential revenue
opportunities.
Technical requirements
Technical cloud architecture requirements should be weighted
against the business requirements.
Performance
As a baseline product, general purpose
clouds do not provide optimized performance for any
particular function. While a general purpose cloud
should provide enough performance to satisfy average
user considerations, performance is not a general
purpose cloud customer driver.
No predefined usage model
The lack of a pre-defined
usage model enables the user to run a wide variety of
applications without having to know the application
requirements in advance. This provides a degree of
independence and flexibility that no other cloud
scenarios are able to provide.
On-demand and self-service application
By
definition, a cloud provides end users with the
ability to self-provision computing power, storage,
networks, and software in a simple and flexible way.
The user must be able to scale their resources up to a
substantial level without disrupting the underlying
host operations. One of the benefits of using a
general purpose cloud architecture is the ability to
start with limited resources and increase them over
time as the user demand grows.
Public cloud
For a company interested in building a
commercial public cloud offering based on OpenStack,
the general purpose architecture model might be the
best choice. Designers are not always going to
know the purposes or workloads for which the end users
will use the cloud.
Internal consumption (private) cloud
Organizations need to determine if it is logical to
create their own clouds internally. Using a private cloud,
organizations are able to maintain complete control over
architectural and cloud components.
Users will want to combine
using the internal cloud with access to an external
cloud. If that case is likely, it might be worth
exploring the possibility of taking a multi-cloud
approach with regard to at least some of the
architectural elements.
Designs that incorporate the
use of multiple clouds, such as a private cloud and a
public cloud offering, are described in the
"Multi-Cloud" scenario, see .
Security
Security should be implemented according
to asset, threat, and vulnerability risk assessment
matrices. For cloud domains that require increased
computer security, network security, or information
security, a general purpose cloud is not considered an
appropriate choice.