Typically migration initiatives into the cloud are implemented in phases or in stages. A structured and process-oriented approach to migration into a cloud has several advantages of capturing within itself the best practices of many migration projects. While migration has been a difficult and vague subject—of not much interest to the academics and left to the industry practitioners—not many efforts across the industry have been put in to consolidate what has been found to be both a top revenue earner and a long standing customer pain. After due study and practice, we share the Seven-Step Model of Migration into the Cloud as part of our efforts in understanding and leveraging the cloud computing service offerings in the enterprise context.

The Seven Step Model of Migration into the Cloud. (Source: Infosys Research.)
1. Conduct Cloud Migration Assessments
2. Isolate the Dependencies
3. Map the Messaging & Environment
4. Re-architect & Implement the lost Functionalities
5. Leverage Cloud Functionalities & Features
6. Test the Migration
7. Iterate and Optimize

Cloud migration assessments comprise assessments to understand the issues involved in the specific case of migration at the application level or the code, the design, the architecture, or usage levels. In addition, migration assessments are done for the tools being used, the test cases as well as configurations, functionalities, and NFRs of the enterprise application. This results in a meaningful formulation of a comprehensive migration strategy. The first step of the iterative process of the seven-step model of migration is basically at the assessment level. Proof of concepts or prototypes for various approaches to the migration along with the leveraging of pricing parameters enables one to make appropriate assessments.

These assessments are about the cost of migration as well as about the ROI that can be achieved in the case of production version. The next process step is in isolating all systemic and environmental dependencies of the enterprise application components within the captive data center. This, in turn, yields a picture of the level of complexity of the migration. After isolation is complete, one then goes about generating the mapping constructs between what shall possibly remain in the local captive data center and what goes onto the cloud. Perhaps a substantial part of the enterprise application needs to be rearchitected, redesigned, and reimplemented on the cloud. This gets in just about the functionality of the original enterprise application. Due to this migration, it is possible perhaps that some functionality is lost. In the next process step we leverage the intrinsic features of the cloud computing service to augment our enterprise application in its own small ways. Having done the augmentation, we validate and test the new form of the enterprise application with an extensive test suite that comprises testing the components of the enterprise application on the cloud as well. These test results could be positive or mixed. In the latter case, we iterate and optimize as appropriate. After several such optimizing iterations, the migration is deemed successful. Our best practices indicate that it is best to iterate through this Seven-Step Model process for optimizing and ensuring that the migration into the cloud is both robust and comprehensive. Figure 2.6 captures the typical components of the best practices accumulated in the practice of the Seven-Step Model of Migration into the Cloud. Though not comprehensive in enumeration, it is representative.

Compared with the typical approach8 to migration into the Amazon AWS, our Seven-step model is more generic, versatile, and comprehensive. The typical migration into the Amazon AWS is a phased over several steps. It is about six steps as discussed in several white papers in the Amazon website and is as follows: The first phase is the cloud migration assessment phase wherein dependencies are isolated and strategies worked out to handle these dependencies. The next phase is in trying out proof of concepts to build a reference migration architecture. The third phase is the data migration phase wherein database data segmentation and cleansing is completed. This phase also tries to leverage the various cloud storage options as best suited. The fourth phase comprises the application migration wherein either a “forklift strategy” of migrating the key enterprise application along with its dependencies (other applications) into the cloud is pursued. Or perhaps using the “hybrid migration strategy,” the critical parts of the enterprise application are retained in the local captive data center while noncritical parts are moved into the cloud. The fifth phase comprises leveraging the various Amazon AWS features like elasticity, autoscaling, cloud storage, and so on. Finally in the sixth phase, the migration is optimized for the cloud. These phases are representative of how typical IT staff would like to migrate an enterprise application without touching its innards but only perhaps at the level of configurations—this perfectly matches with the typical IaaS cloud computing offerings. However, this is just a subset of our Seven-step Migration Model and is very specific and proprietary to Amazon cloud offering.

Source of Information : Wiley - Cloud Computing Principles and Paradigms 2011 


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