Google Professional Cloud Architect Certification: 11. Migration Planning - Important Things To Know

Migration planning requires broad scope planning that ranges from business service considerations to network design planning. It should include planning for integration with existing systems. This itself is a broad topic within migration planning and is best addressed using a five-step plan that includes assessment, pilot, data migration, application migration, and optimization. Before migrating systems and data, it is important to understand dependencies between systems, service level commitments, and other factors that contribute to the risk of migrating a service. Generally, it is recommended to migrate data first and then migrate applications. Migrating databases takes additional planning to avoid data loss or disruption in services during the migration. Review software licenses during migration planning and determine how you will license software in the cloud. Options include bring your own license, pay as you go, or including the license with other cloud charges. Network planning includes planning virtual private clouds, network access controls, scalability, and connectivity.

1. Cloud migrations are inherently about incrementally changing existing infrastructure in order to use cloud services to deliver information services. You will need to plan a migration carefully to minimize the risk of disrupting services while maximizing the likelihood of successfully moving applications and data to the cloud. For many organizations, cloud computing is a new approach to delivering information services. These organizations may have built large, complex infrastructures running a wide array of applications using on-premises data centers. Now those same organizations want to realize the advantages of cloud computing.
2. Know the five stages of migration planning: assessment, pilot, data migration, application migration, and optimization. During the assessment phase, take inventory of applications and infrastructure. During the pilot stage, you will migrate one or two applications in an effort to learn about the cloud and develop experience running applications in the cloud. In the data migration and application migration phases, data and applications are moved in a logical order that minimizes the risk of service disruption. Finally, once data and applications are in the cloud, you can shift your focus to optimizing the cloud implementation.
3. Understand how to assess the risk of migrating an application. Considerations include service-level agreements, criticality of the system, availability of support, and quality of documentation. Consider other systems on which the migrating system depends. Consider other applications that depend on the migrating system. Watch for challenging migration operations, such as performing a database replication and then switching to a cloud instance of a database.
4. Understand how to map licensing to the way you will use the licensed software in the cloud. Operating system, application, middleware services, and third-party tools may all have licenses. There are a few different ways to pay for software running in the cloud. In some cases, the cost of licensing is included with cloud service charges. In other cases, you may have to pay for the software directly in one of two ways. You may have an existing license that can be used in the cloud, or you may purchase a license from the vendor specifically for use in the cloud. This is sometimes referred to as the a BYOL model. In other cases, software vendors will charge based on usage, much like cloud service pricing.
5. Know the steps involved in planning a network migration. Network migration planning can be broken down into four broad categories of planning tasks: VPCs, access controls, scaling, and connectivity. Planning for each of these will help identify potential risks and highlight architecture decisions that need to be made. Consider how you will use networks, subnets, IP addresses, routes, and VPNs. Plan for linking on-premises networks to the Google Cloud using either VPNs or Cloud Interconnect.