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On-Demand Cloud Bursting Made Possible by Architecture

There is a wide variety of use cases for cloud computing, many of which rely heavily upon the particular model of cloud discussed. SaaS (Software as a Service), for example, has a different usage than does IaaS (Infrastructure as a Service), particularly when leveraged in the context of a hybrid cloud data center model.

One of the first use cases for IaaS was centered on the concept of extending the data center on-demand. This was loosely coined as "cloud-bursting" and continues today to be the primary use case upon which many cloud-based solutions are built. This is primarily due to the fact that cloud-bursting -- the ability to extend capacity of existing applications by leveraging cloud-based compute resources dynamically -- requires addressing several technological challenges to become reality, many of which are applicable across the cloud computing spectrum.

The Challenge of Real-Time Migration
When offered an overview of a cloud-bursting­capable architecture, the first question that was raised--and is still often raised--is, "How do you get the application into the cloud in the first place?" Answering this question became a primary concern for solution providers because unless an application could be migrated on demand to a cloud computing provider, the value proposition for cloud-bursting was suspect. If the application had to exist prior to being "bursted" then the organization was paying for resources in the cloud all the time, which negated the proposed cost savings associated with the solution. Thus it became an imperative to address the challenge of migrating an application in real time as a means to enable cloud-bursting without negatively impacting the value proposition of cloud computing.

This process turned out to be a lot harder than anticipated. The assumptions and requirements continue to be restrictive:

  1. Both the data center and the cloud computing environment must utilize the same virtualization platform, or have the means by which an application can be packaged in a cloud computing environment specific container in real time.
  2. The networking layer in both the cloud provider's environment and data center must be bridged as to allow communication with existing infrastructure, ensuring availability and continued operation of delivery infrastructure.
  3. The application package must be transferred across often high-latency WAN links to the cloud computing provider as quickly as possible because limitations integral to migration capabilities of virtualization platforms will cause such a transfer to fail if not completed in a fairly narrow window.
  4. The existence of the new application resource in the cloud computing environment must be made known and subsequently accessible to the infrastructure responsible for directing end users to that instance of the application.

While addressing these issues it has become clear that the transfer of the application from one location to another posed the biggest obstacle to enabling a truly dynamic cloud-bursting-capable infrastructure. That's because a number of underlying technological issues--distance, size of application packaging in virtual containers, and architectural limitations on existing solutions--made it difficult the use well-understood and traditionally used methods to counter those issues.

Using Traditional Solutions in Untraditional Ways
The network--specifically, the external WAN--is at the heart of the challenge when enabling elastic applications that are capable of cloud-bursting on-demand. The very organizations that would benefit most from the cost savings associated with leveraging on­demand cloud computing resources are the same organizations whose Internet-facing network connectivity is likely to be less than optimal in terms of quality and proximity to the Internet backbone. These same network links are utilized by other applications and users as well, which makes it difficult for the organization to ensure the quality and speed necessary to successfully transfer a virtualized application from its data center to an off-premise cloud environment.

The obvious solution is to leverage accepted architectural solutions: WAN optimization technologies. The hurdle with a traditional WAN optimization solution, however, is in the network configuration and deployment, which requires specific placement in both the data center and off-premise location. This is required because WAN optimization solutions use data deduplication to address the challenge of transferring big data across small pipes. This process requires a symmetric deployment model and further requires specific placement of the solution in the network. While the former has been addressed by the virtualization of WAN optimization solutions, the latter is not. Cloud computing providers allow little to no control over topological decisions regarding the deployment of solutions in their environment, making a traditional WAN optimization solution unfeasible.

What is feasible is the use of data deduplication and other WAN-related optimization technologies to improve the conditions of the network connection and simultaneously ensure the successful migration of a virtualized application. Managing data deduplication at a strategic point of control in the architecture becomes necessary to enable the functionality of a WAN optimization solution.

An Architectural Strategy Can Achieve Where Individual Products Fail
By applying WAN delivery services within the context of holistic application delivery, a solution is capable of addressing not only the successful transfer of on-demand of virtualized applications from the data center to the cloud environment, but also the networking and application routing challenges associated with an on-demand cloud-bursting architecture.

On-demand cloud-bursting architectures have been demonstrated as feasible and capable of maintaining cost-reducing benefits with a strategic architecture that optimizes not only layers of the network but the entire process. This comprises triggering the event that initiates the process to monitoring the entire application set across environments as a means to ensure that extraneous cloud-deployed applications are in use only as long as they need be, and no longer.

By architecting a solution rather than deploying individual products to address each challenge, on-demand cloud-bursting has become not only possible but feasible. The challenges associated with leveraging cloud computing in ways that preserve its value proposition will continue to be best answered with a holistic architectural strategy rather than individual tactical product deployments. Such tactical solutions are incapable of providing the visibility, control, and flexibility needed to enable the dynamic infrastructure required to fully take advantage of a dynamic compute resource model such as underpins an on-demand, cloud-bursting solution.

Posted by Karl Triebes on 09/16/2010 at 12:47 PM


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