Overview

In order to understand private cloud and how it differs from other mechanisms for delivering cloud services, it’s helpful to understand what constitutes a “cloud” and how cloud differs from traditional LAN based data centers. The United States National Institute of Standards and Technology (NIST) has put together a definition that a number of cloud architects, designers, implementers and service providers agree upon. The NIST definition of cloud computing, which applies to both public cloud and private cloud environments, requires that a cloud solution enable or provide the following:

• On-demand self-service - The consumer of the cloud service should be able to obtain cloud services (such as compute, memory, network, and storage resources) using a self-service mechanism (such as a web portal) so that acquiring the service does not require human intervention by the Cloud Service Provider (CSP)
• Broad network access - The cloud solution should be accessible from almost anywhere (when required) and also be accessible from multiple form factors, such as smart phones, tablet PCs, laptops, desktops, and any other form factor existing currently or in the future.
• Resource pooling - The cloud solution should host a pool of shared resources that are provided to consumers of the cloud service. Resources such as compute, memory, network, and disk (storage) are allocated to consumers of the service from a shared pool. Resources are abstracted from their actual location, and consumers are unaware of the location of these resources.
• Rapid elasticity - The cloud solution should provide for rapidly provisioning and release of resources as demand for the cloud service increases and decreases. This should be done automatically and without the need of human intervention. In addition, the consumer of the cloud service should have the perception that there is an unlimited resource pool so that the service is able to meet demands for virtually any use case scenario.
• Metered services - Sometimes referred to as the “pay-as-you-go” model, the cloud solution must make it possible to charge the consumer of the cloud service an amount based on actual use of cloud resources. Resource usage is monitored, reported, and controlled by the CSP and by service policy, which delivers billing transparency to both the CSP and the consumer of the service.

When you consider the requirements set forth by NIST, you can now realize that cloud computing is much more than server virtualization, server consolidation or “online services” and that the key factors of self-service, broad network access, resource pooling, rapid elasticity, and metered services all work together to present a new paradigm for service delivery. When these principles are realized in the data center they transform the traditional data center into a private cloud.

Note:
This document is part of a collection of documents that comprise the Reference Architecture for Private Cloud document set. The Reference Architecture for Private Cloud documentation is a community collaboration project. Please feel free to edit this document to improve its quality. If you would like to be recognized for your work on improving this article, please include your name and any contact information you wish to share at the bottom of this page.

Some Advantages of Private Cloud Computing

What are the advantages of private cloud over the traditional data center model? Examples include:

• The on-demand capability enables teams to quickly develop, test and deploy solutions that would otherwise take weeks or months to instantiate in a non-cloud environment. The service team just fills in the online request form, virtual machines with the appropriate computing capabilities are spun up and the team creates the solution – all without the intervention of the private cloud management team.
• The rapid elasticity capability enables you to save money on compute, memory, network, and storage resources because these resources scale up and are released when needed. When projects start, the resources are allocated to consumers of the cloud service, and when the project ends, these resources are released back into the cloud infrastructure’s resource pool.
• The metered services capability makes it possible for IT to be seen as a true service provider and moves IT from a cost-center to a business enabler by monitoring cloud infrastructure resource usage by cloud service consumers and then providing comprehensive reports on usage and charge back to the departments consuming the cloud service.

These are just a few of the advantages enabled by the private cloud. The big difference between traditional data center computing, (where the focus was on infrastructure and operations and “keeping the lights on”) and private cloud is that private cloud computing is all about “service delivery”. The core architecture of any private cloud environment is focused squarely on this central tenet of service delivery.

The Private Cloud as Part of the Journey to Hybrid Cloud

An important thing to keep in mind when thinking about private cloud is that you should think of private cloud as part of your journey to a mixed or hybrid cloud environment, where some of your service assets are hosted in the private cloud and others are located in the public cloud. To get the most out of your investment in private cloud, you should have this hybrid model in mind as we see the norm in the future to be a hybrid cloud environment.

The reason for this is that the transition to a cloud-based environment should lead to the following:

• A focus on a service provider's mindset
• A focus on resiliency instead of redundancy with the goal being to optimize time to service restoration
• Development of applications that fully leverage cloud capabilities
• Development of applications that are "mobile" in that they can easily move between private and public cloud

As your data center transforms from a traditional LAN based model to the new private cloud model, your IT organization will learn many lessons on how to effectively and efficiently run a cloud based operation. The lessons learned during the process of architecting, designing, planning, deploying, and managing the private cloud will provide insights that will benefit you when you are ready to expand your cloud infrastructure to obtain the benefits of a hybrid cloud deployment.

Private Cloud Begins with a Strong Architectural Foundation

For most IT organizations the journey to the cloud will represent a major departure from how they currently do business. Most likely, your current data center is a mixture of what you want and what you don't want. The evolution of your environment to private cloud then presents you an opportunity to architect the service delivery environment you always wanted to have but were not able to realize in your current environment. However, to get the most out of your new private cloud infrastructure, you'll need to build on a strong architectural foundation.

This is where the Reference Architecture for Private Cloud comes in. The collection of documents that comprise this reference architecture helps the IT service provider make the transformational journey to private and ultimately to hybrid cloud. The materials have a solid foundation in key business drivers. They provide a structured approach to making architectural decisions. The aim is to improve the quality of private cloud infrastructure design while realizing the efficiency gains possible with cloud computing.

Summary

Private cloud provides IT a collection of elastic, pooled resources that consumers of the cloud service can access through self-service mechanisms in an environment dedicated to your organization. A private cloud moves the focus toward providing business value through a service providers approach, provides underpinnings of a future expansion to a hybrid cloud, and enables increased scale and flexibility on dedicated resources to provide increased customization and control. The private cloud represents an opportunity to architect your service delivery infrastructure so that the focus changes from "keeping the lights on" through a emphasis on redundancy to a new emphasis on resiliency and time to service restoration. Finally, to realize maximum benefits from investment in private cloud, you'll need to build it on a strong architectural foundation, with the Reference Architecture for Private Cloud helping to provide that foundation.

REFERENCES:
Private Cloud Overview

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