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Comparing Public, Private, and Hybrid Cloud Computing OptionsBy Judith Hurwitz, Robin Bloor, Marcia Kaufman, and Fern Halper from Cloud
Computing For Dummies
Cloud computing comes in three forms: public clouds, private clouds, and hybrids
clouds. Depending on the type of data you're working with, you'll want to compare
public, private, and hybrid clouds in terms of the different levels of security and
management required.
Public Clouds
A public cloud is one in which the services and infrastructure are provided off-site over
the Internet. These clouds offer the greatest level of efficiency in shared resources;
however, they are also more vulnerable than private clouds. A public cloud is the
obvious choice when
Your standardized workload for applications is used by lots of people, such as e-
mail.
You need to test and develop application code.
You have SaaS (Software as a Service) applications from a vendor who has a
well-implemented security strategy.
You need incremental capacity (the ability to add computer capacity for peak
times).
You’re doing collaboration projects.
You’re doing an ad-hoc software development project using a Platform as a
Service (PaaS) offering cloud.
Many IT department executives are concerned about public cloud security and
reliability. Take extra time to ensure that you have security and governance issues well
planned, or the short-term cost savings could turn into a long-term nightmare.
Private Clouds
A private cloud is one in which the services and infrastructure are maintained on a
private network. These clouds offer the greatest level of security and control, but they
require the company to still purchase and maintain all the software and infrastructure,
which reduces the cost savings. A private cloud is the obvious choice when
Your business is your data and your applications. Therefore, control and security
are paramount.
Your business is part of an industry that must conform to strict security and data
privacy issues.
Your company is large enough to run a next generation cloud data center
efficiently and effectively on its own.
To complicate things, the lines between private and public clouds are blurring. For
example, some public cloud companies are now offering private versions of their public
clouds. Some companies that only offered private cloud technologies are now offering
public versions of those same capabilities.
Hybrid Clouds
A hybrid cloud includes a variety of public and private options with multiple providers. By
spreading things out over a hybrid cloud, you keep each aspect at your business in the
most efficient environment possible. The downside is that you have to keep track of
multiple different security platforms and ensure that all aspects of your business can
communicate with each other. Here are a couple of situations where a hybrid
environment is best.
Your company wants to use a SaaS application but is concerned about security.
Your SaaS vendor can create a private cloud just for your company inside their
firewall. They provide you with a virtual private network (VPN) for additional
security.
Your company offers services that are tailored for different vertical markets. You
can use a public cloud to interact with the clients but keep their data secured within
a private cloud.
The management requirements of cloud computing become much more complex when
you need to manage private, public, and traditional data centers all together. You'll need
to add capabilities for federating these environments.
http://thecloudtutorial.com/nistcloudcomputingdefinition.html
Types of cloud computingCloud computing is typically classified in two ways:
1. Location of the cloud computing2. Type of services offered
Location of the cloudCloud computing is typically classified in the following three ways:
1. Public cloud: In Public cloud the computing infrastructure is hosted by the cloud vendor at the vendor’s premises. The customer has no visibility and control over where the
computing infrastructure is hosted. The computing infrastructure is shared between any organizations.
2. Private cloud: The computing infrastructure is dedicated to a particular organization and not shared with other organizations. Some experts consider that private clouds are not real examples of cloud computing. Private clouds are more expensive and more secure when compared to public clouds.
Private clouds are of two types: On-premise private clouds and externally hosted private clouds. Externally hosted private clouds are also exclusively used by one organization, but are hosted by a third party specializing in cloud infrastructure. Externally hosted private clouds are cheaper than On-premise private clouds.
3. Hybrid cloud Organizations may host critical applications on private clouds and applications with relatively less security concerns on the public cloud. The usage of both private and public clouds together is called hybrid cloud. A related term is Cloud Bursting. In Cloud bursting organization use their own computing infrastructure for normal usage, but access the cloud using services like Salesforce cloud computing for high/peak load requirements. This ensures that a sudden increase in computing requirement is handled gracefully.
4. Community cloud involves sharing of computing infrastructure in between organizations of the same community. For example all Government organizations within the state of California may share computing infrastructure on the cloud to manage data related to citizens residing in California.
Classification based upon service providedBased upon the services offered, clouds are classified in the following ways:
1. Infrastructure as a service (IaaS) involves offering hardware related services using the principles of cloud computing. These could include some kind of storage services (database or disk storage) or virtual servers. Leading vendors that provide Infrastructure as a service are Amazon EC2, Amazon S3,Rackspace Cloud Servers and Flexiscale.
2. Platform as a Service (PaaS) involves offering a development platform on the cloud. Platforms provided by different vendors are typically not compatible. Typical players in PaaS are Google’s Application Engine, Microsofts Azure, Salesforce.com’s force.com .
3. Software as a service (SaaS) includes a complete software offering on the cloud. Users can access a software application hosted by the cloud vendor on pay-per-use basis. This is a well-established sector. The pioneer in this field has been Salesforce.coms offering in the online Customer Relationship Management (CRM) space. Other examples are online email providers like Googles gmail and Microsofts hotmail, Google docs and Microsofts online version of office called BPOS (Business Productivity Online Standard Suite).
The above classification is well accepted in the industry. David Linthicum describes a more granular classification on the basis of service provided. These are listed below:
1. Storage-as-a-service2. Database-as-a-service3. Information-as-a-service4. Process-as-a-service5. Application-as-a-service6. Platform-as-a-service7. Integration-as-a-service8. Security-as-a-service9. Management/Governance-as-a-service10. Testing-as-a-service11. Infrastructure-as-a-service