16-11-2012, 05:16 PM
A Berkeley View of Cloud Computing
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Executive Summary
Cloud Computing, the long-held dream of computing as a utility, has the potential to transform a large part of the
IT industry, making software even more attractive as a service and shaping the way IT hardware is designed and
purchased. Developers with innovative ideas for new Internet services no longer require the large capital outlays
in hardware to deploy their service or the human expense to operate it. They need not be concerned about overprovisioning
for a service whose popularity does not meet their predictions, thus wasting costly resources, or underprovisioning
for one that becomes wildly popular, thus missing potential customers and revenue. Moreover, companies
with large batch-oriented tasks can get results as quickly as their programs can scale, since using 1000 servers for one
hour costs no more than using one server for 1000 hours. This elasticity of resources, without paying a premium for
large scale, is unprecedented in the history of IT.
Cloud Computing refers to both the applications delivered as services over the Internet and the hardware and
systems software in the datacenters that provide those services. The services themselves have long been referred to as
Software as a Service (SaaS). The datacenter hardware and software is what we will call a Cloud. When a Cloud is
made available in a pay-as-you-go manner to the general public, we call it a Public Cloud; the service being sold is
Utility Computing. We use the term Private Cloud to refer to internal datacenters of a business or other organization,
not made available to the general public. Thus, Cloud Computing is the sum of SaaS and Utility Computing, but does
not include Private Clouds. People can be users or providers of SaaS, or users or providers of Utility Computing. We
focus on SaaS Providers (Cloud Users) and Cloud Providers, which have received less attention than SaaS Users.
From a hardware point of view, three aspects are new in Cloud Computing.
What is Cloud Computing?
Cloud Computing refers to both the applications delivered as services over the Internet and the hardware and systems
software in the datacenters that provide those services. The services themselves have long been referred to as Software
as a Service (SaaS), so we use that term. The datacenter hardware and software is what we will call a Cloud.
When a Cloud is made available in a pay-as-you-go manner to the public, we call it a Public Cloud; the service
being sold is Utility Computing. Current examples of public Utility Computing include AmazonWeb Services, Google
AppEngine, and Microsoft Azure. We use the term Private Cloud to refer to internal datacenters of a business or
other organization that are not made available to the public. Thus, Cloud Computing is the sum of SaaS and Utility
Computing, but does not normally include Private Clouds. We’ll generally use Cloud Computing, replacing it with
one of the other terms only when clarity demands it. Figure 1 shows the roles of the people as users or providers of
these layers of Cloud Computing, and we’ll use those terms to help make our arguments clear.
The advantages of SaaS to both end users and service providers are well understood. Service providers enjoy
greatly simplified software installation and maintenance and centralized control over versioning; end users can access
the service “anytime, anywhere”, share data and collaborate more easily, and keep their data stored safely in the
infrastructure. Cloud Computing does not change these arguments, but it does give more application providers the
choice of deploying their product as SaaS without provisioning a datacenter: just as the emergence of semiconductor
foundries gave chip companies the opportunity to design and sell chips without owning a fab, Cloud Computing allows
deploying SaaS—and scaling on demand—without building or provisioning a datacenter. Analogously to how SaaS
allows the user to offload some problems to the SaaS provider, the SaaS provider can now offload some of his problems
to the Cloud Computing provider. From now on, we will focus on issues related to the potential SaaS Provider (Cloud
User) and to the Cloud Providers, which have received less attention.
Clouds in a Perfect Storm: Why Now, Not Then?
Although we argue that the construction and operation of extremely large scale commodity-computer datacenters was
the key necessary enabler of Cloud Computing, additional technology trends and new business models also played
a key role in making it a reality this time around. Once Cloud Computing was “off the ground,” new application
opportunities and usage models were discovered that would not have made sense previously.
New Technology Trends and Business Models
Accompanying the emergence ofWeb 2.0 was a shift from “high-touch, high-margin, high-commitment” provisioning
of service “low-touch, low-margin, low-commitment” self-service. For example, in Web 1.0, accepting credit card
payments from strangers required a contractual arrangement with a payment processing service such as VeriSign or
Authorize.net; the arrangement was part of a larger business relationship, making it onerous for an individual or a very
small business to accept credit cards online. With the emergence of PayPal, however, any individual can accept credit
card payments with no contract, no long-term commitment, and only modest pay-as-you-go transaction fees. The level
of “touch” (customer support and relationship management) provided by these services is minimal to nonexistent, but
the fact that the services are now within reach of individuals seems to make this less important. Similarly, individuals’
Web pages can now use Google AdSense to realize revenue from ads, rather than setting up a relationship with an
ad placement company, such DoubleClick (now acquired by Google). Those ads can provide the business model for
Wed 2.0 apps as well. Individuals can distribute Web content using Amazon CloudFront rather than establishing a
relationship with a content distribution network such as Akamai.
AmazonWeb Services capitalized on this insight in 2006 by providing pay-as-you-go computing with no contract:
all customers need is a credit card. A second innovation was selling hardware-level virtual machines cycles, allowing
customers to choose their own software stack without disrupting each other while sharing the same hardware and
thereby lowering costs further.