To migrate on-premises servers to Azure successfully, follow three phases: assess what you have and how it should move, migrate in planned waves with testing and controlled cutovers, and optimize cost, security and performance afterward. Microsoft’s Azure Migrate service supports discovery, dependency mapping, sizing and replication for VMware, Hyper-V and physical servers. The real work is in deciding the right strategy for each application and preparing a secure landing zone first.
Key Takeaways
- Build an Azure landing zone before moving workloads.
- Use Azure Migrate for discovery, dependency analysis and right-sized recommendations.
- Decide a strategy per application: rehost, replatform, refactor, rearchitect, rebuild or retire.
- Migrate in waves grouped by dependencies, with test migrations first.
- Optimize after migration with rightsizing, reservations and Hybrid Benefit.
Phase 1: Assess
- Inventory servers, operating systems, applications, databases and storage.
- Run Azure Migrate discovery and dependency analysis.
- Identify end-of-support systems (for example older Windows Server or SQL Server versions).
- Capture performance data to size Azure VMs accurately.
- Estimate costs, including Azure Hybrid Benefit and reservations.
- Document compliance and data residency needs.
Choose a Strategy for Each Workload
| Strategy | Description | Best for |
|---|---|---|
| Rehost | Lift and shift VMs as-is | Fast datacenter exits |
| Replatform | Minor changes, e.g. SQL to Azure SQL Managed Instance | Reducing management overhead |
| Refactor | Code changes to use PaaS | Apps with active development |
| Rearchitect | Redesign for cloud-native scale | Strategic, high-growth apps |
| Rebuild/Replace | Rewrite or adopt SaaS | Legacy apps with poor fit |
| Retire | Decommission | Unused systems |
Phase 2: Prepare and Migrate
- Deploy an Azure landing zone with networking, identity, policy and monitoring.
- Establish hybrid connectivity (VPN or ExpressRoute) and DNS.
- Group servers into migration waves by dependency and business impact.
- Replicate servers with Azure Migrate.
- Run test migrations in an isolated network and validate apps with owners.
- Schedule cutovers with rollback plans and stakeholder sign-off.
Cutover Checklist
- Freeze changes on source servers.
- Perform final replication and migrate.
- Update DNS, firewall rules and load balancers.
- Validate application functionality and performance.
- Enable backup, monitoring and Defender for Cloud.
- Keep source servers off but available until sign-off.
Phase 3: Optimize
- Rightsize VMs based on actual usage after 30 days.
- Purchase reservations or savings plans for steady workloads.
- Apply Azure cost optimization practices.
- Protect workloads with Azure Backup and Site Recovery.
- Plan modernization for high-value apps.
Common Migration Mistakes
- Migrating without dependency mapping and breaking connected apps.
- Copying on-premises sizing instead of using performance data.
- Skipping the landing zone and fixing governance later.
- Forgetting licensing, backup and monitoring in the cost model.
How Skytech Enterprise Helps
Our server to Azure migration and application modernization services cover assessment, landing zone, wave planning, migration and optimization, followed by Azure managed support. Plan your migration.
Frequently Asked Questions
What is Azure Migrate?
Azure Migrate is Microsoft’s service for discovering, assessing and migrating servers, databases, web apps and virtual desktops to Azure.
How long does a server migration to Azure take?
Small environments can move in weeks; larger estates with many dependencies are migrated in waves over several months.
Can we migrate without downtime?
Replication minimizes downtime, but most cutovers need a short planned window for final sync, DNS changes and validation.
Should SQL Server move to a VM or Azure SQL?
It depends on compatibility and management goals. Azure SQL Managed Instance offers high compatibility with less management; VMs offer full control.
What is Azure Hybrid Benefit?
It allows eligible existing Windows Server and SQL Server licenses to reduce Azure compute costs.
Do we need ExpressRoute?
Not always. Site-to-site VPN suits many organizations; ExpressRoute provides private, more predictable connectivity for larger or latency-sensitive workloads.