The phrases "cloud computing" and "private cloud" have permeated the technical zeitgeist with a rapidity that we have rarely seen. As a result, we spend a good deal of our time discussing these concepts with our customers, partners, and technical colleagues in an effort to understand what they mean in concrete terms. In an effort to bring some clarity to these ruminations (primarily to myself), I've tried to distill them into a "Top 5" list of questions we are asked and to formulate my opinion of how they can, and in some cases should, be answered.
First, the questions in dramatically paraphrased form are:
- What is a "private cloud" and how is it different from a "public cloud" and a "virtualized data center?"
- Is a private cloud secure?
- How do I build a cloud?
- How do turn a private cloud into a hybrid cloud?
- What will I need to do to my applications to get them to run in a cloud, private or public?
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He is wright. In my perspective, to this list of primordial questions on cloud computing, the following ones deserve to be added.
How do I choose among the type of cloud to be used in my company?
Is there any additional infrastructure needed to deploy a cloud?
These are excellent follow-up questions. Thanks for asking them.
There are several answers to the question "How do I choose among the type of
cloud to be used in my company?" If the choice is between a public and a
private cloud, there there are three popular points of differentiation:
privacy level, cost, and degree of needed customization.
Many companies chose private clouds over public clouds based on the need for
privacy and security. There are many ways to secure data in a public cloud,
but ultimately physical security under the control of the public cloud client
cannot be implemented. In a private cloud, the cloud platform must respect
the locally defined security policies, including those defined for physical
security. That is, a private cloud can and should implement and conform to
all local security policies.
Cost is a second differentiator. Due to economies of scale, cloud occupancy
in public clouds can be made fairly inexpensive when compared to the cost of
siting and maintaining hardware. "Pay-as-you-go" pricing, however, scales
linearly with usage while the maintenance cost by the hosting provider scales
sublinearly thereby generating the profit from scale. Alternatively, private
infrastructure has a high initial buy-in cost followed by sublinear on-going
costs during amortization. To understand the cross-over point, if there is
one, a company needs to be able to make a reasonable estimate of its own
infrastructure costs over time. It must also be able to justify the initial
purchase and siting costs to determine if a complete outlay is, itself, a
cost.
The third factor is the degree of customization that the company desires.
Increasingly, public clouds are serving a form of commodity infrastructure.
Commodities drive the price down, but by their definition they are not very
diverse. Often innovation requires a customization that deviates from what is
available as a commodity. In terms of infrastructure, a private cloud can be
customized in support of this need for innovation. The decision point, then,
revolves around the need for a non-commodity computing, networking, and
storage infrastructure.
As far as additional infrastructure goes, it depends on the cloud platform as to
what hardware and software needs to be available and how it is configured.
Speaking only for Eucalyptus, standard x86 platforms running any of several
Linux distributions are supported, interconnected by ethernet, with locally attached disk
storage in the open-source platform. We extend the range of hardware that is supported
in some of our proprietary products (c.f. the EEE).
Thanks again for your excellent comment.
Rich