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If you attended one of our Live Private Cloud TechNet events delivered recently in the major metros along the US east coast, hopefully we’ve inspired you to build out your own private cloud test environment with downloadable evaluation products. This is the 2nd episode of our post-event conference call as a follow-up to further discuss building private cloud with Windows Server 2008 R2 SP1 and System Center 2012. For those who are interested, there are also additional information, free ebooks, and posters available to better understand some of the enabling technologies of cloud computing.
Amid the many benefits of having the NIST SP 800-145 as a tool to facilitate the understanding, the classification and some definitions of the four deployment models are redundant and inconsistent. Particularly, the definition of “community cloud” is a redundant of that of a private cloud, the deployment models are defined with 2 set of criteria, and “hybrid cloud” is a confusing, ambiguous, and extraneous term.
SP 800-145 is the de facto standard in IT industry of describing what cloud computing is with five essential characteristics, three delivery methods, and four deployment models. The five essential characteristics well specify the qualifications and expected behaviors of an object qualified with the term, cloud. The three delivery methods signify the essence of cloud computing centered on the concept of a “service.” Both the characteristics and the delivery methods in SP 800-145 form a solid foundation and present a conceptual model envisioning what cloud computing is and about. SP 800-145 gets inconvenient where the four deployment models including public, community, private, and hybrid clouds are defined, as shown below.
The Premise
Reviewing the definitions of the first three deployment models, there is a common theme. Among public, community, and private clouds, the classification is based on the intended audiences whom a cloud with its resources is dedicated to. Namely, a public cloud is intended to be consumed by the general public and a private cloud is dedicated to a single organization, i.e. for a targeted group of users. SP 800-145 classifies a private cloud and a public cloud with consistent criteria.
It is important to recognize that building a cloud with owned hardware does not default it as a private cloud of the owner’s, while a cloud with accessibility via Internet or operated by an internet service provider does not automatically make it a public cloud either. Again, the intended audiences determine it is a private or public cloud. Although many seem to default a private cloud as an on-premise deployment to owned hardware, this is nonetheless not a requirement of a private cloud.
Further “public” here does not suggest that it is free or accessible anonymously. It simply means the cloud is dedicated for the general public to consume, while there can be business or administrative restrictions imposed. Microsoft Office 365 available based on a subscription and Hotmail requiring a Live ID to sign are vivid examples of public cloud offerings with restrictions.
Inconvenience #1: The classification of “community cloud” is extraneous.
A community cloud according to 800-145 is a cloud for a specific community of consumers from organizations. As far as a member of the associated community is concerned, a community cloud is indeed a private cloud for that particular community. The number of the organizations and the administrative boundaries encompassing a community are irrelevant since from a private cloud’s view point, an authorized user is an authorized user regardless which organization one belongs to. A cloud for a community of users from either various departments, business units within a company or business partners from companies in many parts of the world is essentially a private cloud dedicated for that community.
Inconvenience #2: Using two sets of criteria to define cloud deployment models roots inconsistency and ambiguity.
As defined in SP 800-145, a hybrid cloud is a composition of infrastructures, yet at the same time a private cloud and a public cloud are defined according to their intended audiences. The change of criteria in classifying a hybrid cloud roots inconsistency and ambiguity in the deployment models presented in SP 800-145. Forming a concept with two sets of criteria is simply a confusing way to describe an already very confusing subject like cloud computing.
Inconvenience #3: "Hybrid cloud" is an ambiguous, confusing, and frequently misused term.
A hybrid cloud is a composition of two or more distinct cloud infrastructures (private, community, or public) as stated in SP 800-145. That is to say that a hybrid cloud can be a composition of private/private, private/community, private/public, etc. From a consumer’s point of view, they are in essence a private cloud, a private cloud, and a public or private cloud respectively. Regardless how a hybrid cloud is constructed, if it is intended for public consumption it is a public cloud, and if for a particular group of people it is then a private cloud according to SP 800-145. Essentially the composition of clouds is still a cloud and it is an either public or private cloud, and cannot be both at the same time.
For many enterprises IT professionals, a hybrid cloud means an on-premise private cloud connected with some off-premise resources. Notice these off-premise resources are not necessary in reality a cloud. In such case, it is simply a private cloud with some extended boundaries. A cloud is a set of capabilities and must be referenced in the context of the delivered application. Just placing a VM in the cloud or referencing a database placed in the cloud does not make the VM or the database itself a public cloud application.
The key is that a hybrid cloud is a derived concept of clouds. Namely, a hybrid can be integrations, modifications, extensions, or a combination of all of cloud infrastructures. A hybrid is nevertheless not a new concept or a different deployment model and should not be classified as a unique deployment model in addition to the two essential ones, i.e. the public and private cloud models. A cloud is either public or private and there isn’t a third kind of cloud deployment model based on the intended users.
“Hybrid cloud” is perhaps a great catchy marketing term. For many, a hybrid seems to suggest it is advanced, leading edge, and magical, and therefore better and preferred. The truth is "hybrid cloud" is an ambiguous, confusing, and frequently misused term. It confuses people, interjects noises into a conversation, and only to further confirm the state of confusion and inability to clearly understand what cloud computing is.
Virtualization vs. private cloud has confused many IT pros. Are they the same? Or different? In what way and how? We have already virtualized most of my computing resources, is a private cloud still relevant to us? These are questions I have been frequently asked. This is the 2nd article of the series, as shown below, which answers these specific questions.
Be Mindful on What Is Private Cloud
Above all, a private cloud is a deployment model of cloud computing. And since it is cloud computing, the 5-3-2 Principle or NIST SP-800-145 as preferred, applies. When one claims having a private cloud, we can easily verified if it actually is by a few simple questions. Is it delivered with (or at least a flavor of) SaaS, PaaS, or IaaS? Does it has a self-servicing component? Is there resource pooling and is it elastic? Namely standardization, optimization, and automation of resource management are implemented in the underlying infrastructure, such that a fabric-like abstraction can be formed with resource pools to possibly offer location transparency. Which is a private cloud or a cloud application in general must exhibit.
Notice that the hardware ownership is not a criterion. For a private cloud, hardware ownership is not a necessary, but a sufficient condition. One does not need to own the hardware to have a private cloud. Nonetheless, many seems to implicitly assume hardware ownership is part of a private cloud. This is likely due to for enterprise IT to transition into a private cloud environment, the logical approach is to, as applicable, assess and convert what has been established into a private cloud. In such case, likely the infrastructure is already owned and operated by the IT department.
Be Clear on What Private Cloud Delivers
A private cloud is a cloud with the cloud infrastructure dedicated to an organization. On premises or hosted by a 3rd party, a private cloud is expected to exhibit three, if not more, of the five essential characteristics of cloud computing: resource pooling, rapid elasticity, and self-service to differentiate itself from highly virtualized computing. The point is as far as virtualization is concerned, the three key attributes: resource pooling, elasticity, and self-service are not necessary conditions. While for a private cloud, the three are. Reviewing the 5 characteristics which cloud computing delivers, you will notice that I do not include ubiquitous access and consumption-based chargeback model as the key attributes for a private cloud. These two are not considered as essential due to: for a private cloud, the owning organization may want to restrict the availability, instead of allowing ubiquitous access; and a chargeback model may not be administratively necessary or technically feasible, for example, to be implemented in an organization. The following depicts the concept:
Closing Thoughts
There is no question that virtualization is a key technology enabler in transforming to a cloud environment. Without having a technically-mature and economically-affordable virtualization solution in place, cloud computing will be more a concept than an implementation. Nonetheless, make no mistake about it. virtualization is not, and in fact far from, a private cloud. Without resource pooling, elasticity, and self-servicing mechanism to fundamentally design efficiency into cloud architecture and minimize the overhead, implementing a private cloud can quickly become cost-prohibitive and without a predictable ROI in the long run. With these the key attributes and a virtualization solution, a private cloud therefore forms.
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More hybrid cloud resources at http://aka.ms/all.
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December, 2011 - Yung Chou on Hybrid Cloud - Site Home - TechNet Blogs