Migration Sequencing Error — Azure Solutions Architect (AZ-305)
You got the migration order wrong. Dependencies, data gravity, and blast radius determine sequence.
DMS Online Mode vs. Data Box for SQL Server Migration
'Continuous replication' and 'minimal cutover window' together point to Azure Database Migration Service in online mode: it maintains live replication from the source SQL Server through the final cutover, keeping downtime measured in minutes. Azure Data Box solves a different problem, offline bulk physical data transfer for petabyte-scale datasets where network transfer is impractical. Both are valid Azure migration tools. The question is which phase of migration the scenario is describing. Read the downtime and volume constraints before comparing services. The phase signal is always present; find it before evaluating service capabilities.
The Scenario
A company is migrating their DevOps toolchain to Azure DevOps. You recommend starting with Azure Pipelines because the team is most excited about managed CI. But the pipelines depend on an on-premises Artifactory for package management and deploy to on-premises servers via custom scripts. Moving the build pipeline first means every build fetches dependencies across a VPN from Artifactory (slow), and deployments still target on-premises infrastructure (no Azure benefit). The correct sequence: (1) Migrate the artifact repository to Azure Artifacts first, (2) Set up deployment targets in Azure (App Service, AKS, or VMs), (3) Migrate pipelines last with updated package sources and deployment targets. The pipeline is the consumer of artifacts and deployment targets — it should move after its dependencies, not before.
How to Spot It
- •DevOps toolchain migration follows the same dependency rules as application migration. Package repositories and deployment targets are dependencies. Pipelines consume them. Migrate dependencies first so the pipeline has something to pull from and push to when it moves.
- •Azure DevOps migration: Azure Repos (source control) and Azure Artifacts (packages) should migrate before Azure Pipelines. Boards and Test Plans can migrate independently since they have fewer technical dependencies.
- •When the exam describes migrating a CI/CD toolchain, identify what the pipeline depends on: source code repository, package feeds, secrets/credentials store, and deployment targets. Each dependency should be available in Azure before the pipeline migrates.
Decision Rules
Whether to assign Azure Database Migration Service in online mode to the database tier as Wave 1 — before the web tier — or to use Azure Site Recovery for both tiers in a single wave, which both violates the dependency ordering constraint and replicates the SQL Server VM rather than migrating the database to a managed PaaS target.
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Related Patterns