Overview

What Is Application Migration to the Cloud?

Application migration to the cloud is to migrate the access layer, application layer, middleware layer, and data layer of applications to the cloud by using the rehost or replatform strategy without refactor (or re-architect). The data layer includes object storage, block storage, file storage, relational databases, and non-relational databases.

The following figure shows the process of application migration to the cloud.

Figure 1 Small cycle of application migration

In the preceding process, each migration batch contains one or more application migration groups. You need to repeat the preceding process to migrate all applications in a migration batch to the cloud.

Figure 2 Migration in batches

A small cycle consists of the following phases:

• Survey: Conduct a detailed survey on the technical architecture of applications, including their components and versions.
• Design: Provide the technical architecture and specifications on the cloud based on the survey result, and offer a detailed migration and cutover solution.
• Deployment: Create cloud resources, perform cloud adaptation and reconstruction (if required), and test the target environment.
• Migration: Migrate applications and data to the target environment on the cloud.
• Verification: Verify data and services.
• Cutover: Perform mock cutovers, update the runbook, and perform the real cutover.
• Assurance: Perform real-time monitoring and special O&M assurance for a certain period of time after the service cutover.

Survey

In the small cycle of application migration, information of an application needs to be surveyed. The survey results of previous phases can be reused.

The obtained information should be detailed enough to guide migration implementation.

For details about the survey method, see Application System Survey. The technical architecture and component details of an application need to be obtained.

Figure 3 Application survey