Cloud computing is a computing mode that enables on-demand access from anywhere to a shared pool of computing resources. The services can be rapidly provisioned and can be released with minimal interaction from the IT staff or service provider. There are five essential characteristics that define cloud computing.
- on-demand self-service: this allows users to access and provision the resources of the cloud automatically without requiring any additional human interaction.
- broad network access capabilities are generally available over the internet through a standard portal that’s accessible by any device that’s connected to the network
- multi-tenancy: multi-level control structures need to be in place that enable different organizations to securely share resource pools. Each organization can further control access to their resources.
- rapid elasticity ensures the cloud can scale to meet the level of user demand
- metering tracks the level of resource usage or the cost of that usage
Types of Clouds
Cloud computing can take place outside your company or inside your firewall. In general, the options are public, private, or hybrid clouds. Public cloud means that the cloud infrastructure is owned, managed and operated by a cloud service provider and runs on its premises. Private cloud means that the infrastructure is owned, managed and operated by an organization for its own use. Ownership, location and operation can be outsourced to a third party but the overall responsibility for definition of services and acquisition of physical resources remains with the enterprise. Hybrid cloud allows a user to access public and private cloud resources from a single management environment.
IT services and Cloud
There are three distinct types of IT services that enterprises both deliver and use today through public, private and hybrid clouds. The first is software as a service or SaaS. SaaS enables users to access an application but they have little or no control over the delivery of the application. An example of SaaS is Gmail or salesforce.com.
The second is platform-as-a-service or PaaS. PaaS enables users to employ infrastructure applications on to the cloud through a framework of programming languages, libraries, services and tools that are supported by the provider. The user has control over the deployed applications and may also have some control over the configuration settings for the application hosting environment but they don’t control the underlying infrastructure. An example of a public Paas is Windows Azure or CloudFoundry. An example of a private one is the Windows Azure Platform Appliance.
The third cloud service and the one that’s most widely viewed as a cloud is infrastructure as a service or IaaS. IaaS cloud enables a user to dynamically provision computing, storage, networking and other fundamental computing resources where the user does not manage or control the underlying infrastructure.
Public IaaS cloud offerings, most notably Amazon and Rackspace, grew rapidly because of the need for on-demand computing resources that internal IT departments weren’t capable of providing quickly enough. They provided a solution where any individual or company, large or small, could provision a server themselves when they needed it, run up for as long as they needed it, and then shut it down. Because these public cloud providers purchase hardware and software and run the infrastructure and their data centers companies have no upfront capital expense. They pay the cloud service provider and ongoing operational costs for only the computing resources that they need.
Enterprises and Cloud Computing
Initially enterprises we’re looking at public IaaS providers as a way to get access to compute resources for a short period of time without paying the upfront capital expense of a server. But once people started using infrastructure cloud computing they recognized the other benefit: being able to respond more rapidly to changes in demand. This was really nice if, for example, all of a sudden your website had a lot more traffic on it because of a promotion you’re running or because your business was featured in the news. If you’rerunning on a traditional IT infrastructure, where you’re managing servers on a server by server basis, it can be really hard to respond to those changes quickly. On the other hand, in a cloud it’s relatively simple to say spin up more virtual machines and deliver the capacity that you need.
This notion that the business could be more agile start to get the attention of enterprises. Once enterprises started to see that value they started to look at how they could build their own cloud type infrastructures inside the firewall. Private IaaS cloud helps an organization to better control security of data and ensure compliance with regulations. It also makes much more efficient use of the enterprise’s physical infrastructure. In a physical server only environment the enterprise is lucky if they get an average of 25% resource utilization. In a virtualized environment this may push the resource utilization up to the 50 percent range. Cloud computing with this increased levels of automation can get utilization to 75 percent or even higher. By increasing the overall utilization of their servers, enterprises should be able to drive down capital expense. At the same time the computing environment becomes more productive by allowing system administrators to manage a larger number of virtual servers than they otherwise could have. This provides enterprises with long term operational expense as well as capital expense savings. Also, enterprises can react much more rapidly to reconfigure their environment, responding quickly to changes due to external or internal events.
Private cloud makes it much easier to shut down certain workloads or rapidly deploy new workloads rather than having to create new capacity or install new servers. You just start up some new virtual servers and you reallocate the resources in your cloud. That’s much easier to do in a fully virtualized private cloud environment than with partially virtualized or physical environments. Enterprises can do this in-house where they control the data and the security and where they can minimize compliance risks. Whether deploying workloads in the public infrastructure as a service cloud environment or in a private one, or in both, enterprises have the ability to develop a more flexible and agile infrastructure that better aligns to the needs of the business while reducing costs.