7 Rs of database migration

The 7 Rs of database migration are a collection of tactics for planning and carrying out a database migration project. These tactics aid in decision-making and offer a foundation for effective database migration.

Here are the seven Rs:

1. Rehost
   Rehosting, also referred to as lift-and-shift, is a database migration technique in which the database is transferred from the source environment to the destination environment without being altered or changed.

2. Relocate
   Relocation, also known as hypervisor-level lift and shift, is a database migration strategy that involves moving the database from one platform to another. On AWS, this migration scenario is unique to VMware Cloud, which offers workload mobility between your on-premises infrastructure and AWS as well as virtual machine (VM) compatibility. When you move your infrastructure to VMware Cloud on AWS, you can use the VMware Cloud Foundation technologies from your on-premises data centers.
   Relocate focuses on relocating the database to a different location for reasons such as improving performance, disaster recovery, or data center consolidation.

3. Replatform
   Replatforming is also known as lift and reshape; it consists of moving a program to the cloud (or target databases) and optimizing it to take advantage of cloud (or target) features.
   An application of replatform can be to migrate your on-premises Oracle database, for example, to Amazon RDS for Oracle in the AWS Cloud.

4. Repurchase
   The Repurchase refers to shifting from one database product to another by acquiring a new commercial database product or adopting a different database technology. The repurchase method is frequently used when the present database product no longer fits the needs of the firm or when specific features, scalability, performance, or cost concerns are required. For example, move your client data from your on-premises customer relationship management (CRM) system to Salesforce.com.

5. Refactor
   In database migration, Refactor refers to the strategy of restructuring the existing database schema, code, or design without changing the underlying platform or technology. The goal of the Refactor strategy is to improve the efficiency, performance, maintainability, or scalability of the database system.
   The target database's structure is used to determine changes.

6. Retain
   Retain strategy refers to the decision of keeping the existing database system as it is without making any changes or migrations. This strategy is chosen when there is no immediate need or benefit to migrate the database, or when the cost, effort, or risks associated with migration outweigh the potential advantages.

7. Retire
   The "Retire" strategy refers to the choice to retire or decommission a database that is no longer required or relevant.This strategy involves identifying and removing databases that are redundant, outdated, or no longer serving a purpose within the organization.

Each of these strategies has its own set of concerns, advantages, and disadvantages. The proper strategy is determined by elements such as business requirements, technical feasibility, cost consequences, and long-term objectives. For database migration projects to be successful, careful planning, risk assessment, and stakeholder involvement are required.