Welcome to Cloud 101, a course on Cloud Computing. The intent of this course is to provide buyers of Cloud Computing with enough knowledge to purchase the appropriate Cloud Computing service for their business, and deploy their software on it. The class is going to be created on-the-fly in a blog format, so your feedback and comments will help to direct it towards your needs.

- a basic understanding of what is inside a computer system (CPU, memory, disks)

- a basic understanding of computer networking and the Internet

- a basic understanding of how software is developed and deployed

Feel free to skip any lesson in the series, or to jump around as your interests guide you. The first paragraph of each lesson will give you an idea of the topic material it covers.

Ask ten people what they think Cloud Computing is, and you’ll get ten different answers. This makes it exceedingly difficult to talk about it. It also makes it difficult for customers to compare, buy, and pay for it as well as for vendors to sell it. So before we get into the details, it makes sense to agree on at least a general definition of what Cloud Computing is.

Everyone talks about three basic characteristics of Cloud Computing:

1) Abstracted: In the past, if you wanted computing you’d buy or lease a computer. With the hardware (the computer) abstracted into service, you can now buy computing, which is what you wanted in the first place!

2) Scalable or Elastic: Unlike older ways of buying computing – where you had to buy a computer which gave you a fixed amount of computing power – with Cloud you can scale your computing usage up and down as your needs change and avoid having to overbuy to prepare for future needs. In the past, scaling meant changing out hardware, but now it’s as simple as clicking a button on a web page, or even just setting a policy whereby the amount of computing follows the demands for it.

3) Pay-as-you-go or utility billing: Since you can change how much computing you buy over time, it makes sense that it be sold to you like electricity, where you only pay for what you use

There are other characteristics that people often rely on and hold important about Cloud. These characteristics depend a lot on which cloud vendor you choose, and we will discuss them further during the class.

4) Uptime: Cloud is often assumed to be more reliable than simply leasing or buying a server or servers and putting them to work in your business, in part because experienced professionals are providing the service, and in part because the technology used to provide it is more sophisticated than simply one or more computers hooked together.

5) Security: Cloud is often assumed to be more secure or less secure than owning/leasing your own computer – depending on what the expectations are.

6) Cost: Cloud is often assumed to be cheaper than owning/leasing your own computer. Also, TCO (total cost of ownership) of a cloud-based IT strategy is assumed to be lower than having an IT department that owns its own computers.

People often categorize Cloud Computing into three levels of use model (or Cloud Computing services.) All of them satisfy the three characteristics listed above (#1-#3). The chart below shows how the three levels of cloud computing create the service the end user of the application software sees, and how it was provided before the days of Cloud Computing.

1) Infrastructure-as-a-service (IaaS): Cloud Computing replaces bare computer hardware. Customers manage their “cloud computers” from a system administration level, but don’t worry about setting up or maintaining any hardware. The user of IaaS is the person who would have bought the computer before Cloud Computing existed. Examples are companies such as a Amazon, ENKI, GoGrid.

2) Platform-as-a-service (PaaS): Cloud Computing replaces an execution environment for a computer language by providing a system ready to execute the user’s software. The user of PaaS is the programmer. Note that by installing the execution environment into an IaaS service, you produce your own PaaS service. Many choose to go that way because they have more control over the software environment. Examples are companies such as Engine Yard or Google.

3) Software-as-a-Service (SaaS): The user interacts directly with the Cloud-hosted software, and often pays for “seats” or “users” instead of computer time. Examples are NetSuite, SalesForce.com, Google Apps

These models are not exclusive, and can even be combined in many ways: for example, you may use SaaS from a company that purchases IaaS, or you may use software that your own administrators maintain but runs on an IaaS service from a cloud provider. How you use Cloud Computing really depends on where it can make a positive difference.in your value chain (how you do your work or create your product/service.)

This course will focus on Cloud Computing that is sold by the resource-hour, such as a CPU-hour or Memory-hour, Disk-usage-hour, etc. which is typically IaaS.

Another way to look at Cloud Computing is that it is a way to bring the benefits of the latest technological advances and economies of scale that a large corporate datacenter would have, to customers who cannot afford such a large expense. These technological advances include computer virtualization, multi-core servers, I/O virtualization, high capacity and performance storage, and automated management of the datacenter to provide failover and disaster recovery automatically. Large datacenters also enjoy economies of scale by eliminating middlemen and buying in bulk, savings which the average co-location customer simply cannot access.

Cloud Computing is a way to aggregate demand for data center services run under a highly automated virtualization management framework in such a way that users enjoy economies of scale and best-of-breed IT experiences without having to build the infrastructure for themselves.

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