Azure Migration Services and Tools
Key Takeaways
- Azure Migrate is the central hub that discovers, assesses, and migrates servers, databases, web apps, and virtual desktops to Azure.
- Azure Database Migration Service (DMS) moves SQL, MySQL, PostgreSQL, and other databases with offline (downtime) or online (near-zero downtime) modes.
- Azure Site Recovery can perform region-to-region or on-premises-to-Azure migrations in addition to disaster recovery.
- The Data Box family (Disk 8 TB, Data Box 80 TB usable, Heavy 1 PB) handles large offline transfers when bandwidth is limited.
- Microsoft's Cloud Adoption Framework migration journey is Assess, Migrate, Optimize, then Secure and Manage.
Quick Answer: Azure Migrate is the free central hub for discovery, assessment, and migration. Azure Database Migration Service (DMS) moves databases. The Data Box family ships physical disks for huge offline transfers. The Cloud Adoption Framework migration journey runs Assess to Migrate to Optimize to Secure and Manage.
Azure Migrate: the central hub
Azure Migrate is a free service (you pay only for the Azure resources you eventually run) that gives you one place to inventory, plan, and execute a move to Azure. AZ-900 expects you to recognize it as the starting point for any migration scenario. It deploys a lightweight appliance in your on-premises environment that continuously discovers servers, gathers performance metrics (CPU, memory, disk, network), and maps dependencies between machines so you do not strand a database its app still needs.
What Azure Migrate covers
| Tool inside Azure Migrate | What it does |
|---|---|
| Discovery and assessment | Inventories servers, checks Azure-readiness, recommends VM sizes |
| Server migration | Replicates and migrates VMware, Hyper-V, physical, AWS EC2, GCP VMs |
| Database assessment | Flags compatibility issues for SQL Server before migration |
| Web app assessment | Evaluates ASP.NET/Java apps for Azure App Service |
| Azure Virtual Desktop assessment | Sizes and prices an AVD deployment |
An assessment produces three things the exam likes to test: Azure-readiness (ready, ready with conditions, or not ready), a right-sized SKU recommendation, and a monthly cost estimate. Right-sizing is why a 32 GB on-premises server might be recommended as a smaller Azure VM — Azure Migrate uses actual utilization, not provisioned capacity.
Azure Database Migration Service (DMS)
DMS is a fully managed service for migrating databases at scale. Know the source-to-target pairs and the two modes.
| Source | Common Azure target |
|---|---|
| SQL Server | Azure SQL Database, SQL Managed Instance, SQL on Azure VM |
| MySQL | Azure Database for MySQL |
| PostgreSQL | Azure Database for PostgreSQL |
| MongoDB | Azure Cosmos DB (MongoDB API) |
| Mode | Behavior | Downtime |
|---|---|---|
| Offline | Back up, restore, then cut over | Hours to days |
| Online | Continuous replication, cut over when caught up | Minutes (minimal) |
Worked example: A retailer must move a 2 TB SQL Server database with a strict 5-minute outage window during a holiday freeze. Offline migration would blow the window, so you choose online migration — DMS keeps the Azure target in sync while the source stays live, and you cut over during the short window. If the same database were a dev copy nobody uses at night, offline is cheaper and simpler.
The Data Box family: offline transfer
When you must move tens of terabytes or more and your internet link is slow, copying over the wire could take weeks. Azure Data Box is the physical answer — Microsoft ships you a ruggedized, encrypted device, you copy data locally, and ship it back.
| Device | Usable capacity | Typical use |
|---|---|---|
| Data Box Disk | 8 TB per disk (up to 5 disks = 40 TB) | Small/medium transfers |
| Data Box | 80 TB usable (100 TB raw) | Large transfers |
| Data Box Heavy | 1 PB | Very large transfers |
Workflow: order in the portal, Microsoft ships it, you copy data over local SMB/NFS, ship it back, Microsoft uploads it to your storage account, then securely wipes the device to NIST standards.
Migration strategies — the 5 Rs
Microsoft frames every workload move as one of five strategies. The exam tests your ability to match a scenario to the right one, trading migration speed against cloud-native benefit.
- Rehost (lift and shift): move VMs as-is to Azure IaaS with no code changes. It is the fastest path and the lowest risk, but you keep your existing operating costs and gain no PaaS advantages. Choose it when a data center lease is ending and you simply need out fast.
- Refactor: make minor changes so the app runs on PaaS such as Azure App Service or Azure SQL Database. You shed some patching and server management without rewriting business logic.
- Rearchitect: redesign the application for cloud-native patterns such as microservices, containers (Azure Kubernetes Service), or serverless (Azure Functions). Higher effort, higher long-term payoff.
- Rebuild: discard the old code and build fresh as a cloud-native app.
- Replace: retire the application entirely and adopt a SaaS product such as Dynamics 365 instead.
The Cloud Adoption Framework migration journey
Azure Migrate fits into Microsoft's Cloud Adoption Framework (CAF) migration journey. The exam may phrase the phases as Assess, Migrate, Optimize, and Secure and Manage:
| Phase | Key actions |
|---|---|
| Assess | Inventory workloads, map dependencies, estimate Azure cost with the TCO Calculator |
| Migrate | Choose a strategy (the 5 Rs), replicate, cut over, and validate |
| Optimize | Right-size VMs, apply Reserved Instances and Azure Hybrid Benefit, tier cold data |
| Secure and Manage | Turn on Microsoft Defender for Cloud, Azure Policy, monitoring, and backup |
The Total Cost of Ownership (TCO) Calculator is a planning tool you should associate with the Assess phase: it compares your current on-premises spend against an equivalent Azure deployment so leadership can justify the move. Right-sizing during Optimize is where the savings land — Azure Migrate already gathered the utilization data needed to drop oversized VMs to smaller SKUs.
On the Exam: "Large data, limited bandwidth, move to Azure" = Data Box. "Discover and assess on-premises servers" = Azure Migrate. "Migrate a database with minimal downtime" = DMS online migration. "Move VMs with no code changes" = Rehost. "Estimate cost savings before migrating" = TCO Calculator.
An organization needs to move 200 TB of archival data to Azure but has a slow internet connection that would take months to upload. Which service is the best fit?
Which migration approach moves on-premises applications to Azure VMs without any code changes?
A team must migrate a production SQL Server database to Azure SQL Managed Instance with only a few minutes of downtime. Which option meets the requirement?