Azure Cloud Modernization & Brownfield

Rehost (Lift & Shift)

When to Use:

• Datacenter exit (lease/hardware end)
• Legacy apps
• Short timelines
• Compliance deadlines

When NOT to Use:

• Performance issues exist
• Hardware dependencies
• Licensing issues
• Rarely used apps (retire instead)

Workload	Migration	Key Decisions
Windows File Server	Azure VM + Azure Files	Use File Sync
Linux Apache	Azure VM	Consider App Service
Oracle DB	Azure VM	Or refactor to PostgreSQL
.NET Framework App	Windows VM	Later refactor

Steps:

• Inventory dependencies
• Choose VM size
• Migrate via Azure Migrate
• Configure networking
• Enable monitoring & backup
• Cutover DNS
• Optimize post-migration

Pitfalls:

• Over-sized VMs
• Hardcoded IPs
• Missing SSL certificates
• Forgot dependencies

Refactor (Lift & Optimize)

On-Prem	Target	Changes
.NET Framework	App Service	Update config, Managed Identity
SQL Server	Azure SQL	DMA + connection updates
Java Tomcat	App Service Linux	WAR deployment
MySQL	Azure MySQL	DMS migration

Steps:

• Run compatibility assessment
• Update connection strings
• Replace storage & secrets
• Deploy to staging slot
• Swap to production

Pitfalls:

• Unsupported frameworks
• Local storage issues
• Session state problems
• Windows Auth limitations

Rearchitect (Redesign)

Monolith	New Architecture	Changes
.NET Monolith	Microservices (AKS)	Domain split
Java EE	Spring Boot	Rewrite
Batch Jobs	Event-driven	Functions + Service Bus

Strangler Pattern:

• Use API gateway
• Gradually replace modules
• Route traffic incrementally

Pitfalls:

• Too many microservices
• Shared databases
• No observability
• Big-bang rewrite

Other Strategies

• Rebuild: Rewrite fully cloud-native
• Replace: Use SaaS (e.g., CRM → Dynamics)
• Retain: Keep on-prem, manage via Azure Arc

Windows Workloads

Server Role	Azure Target	Method
IIS	App Service / VM	Refactor/Migrate
SQL Server	SQL MI / SQL DB	DMS
File Server	Azure Files	File Sync
AD	Entra ID	Hybrid

Linux Workloads

Workload	Target	Method
Apache/Nginx	App Service / VM	Migrate
Node.js	App Service	Deploy
PostgreSQL	Azure PostgreSQL	DMS
Containers	AKS	Re-deploy

SQL Server Migration

Scenario	Target
Single DB	Azure SQL
Instance features	SQL Managed Instance
Full control	SQL on VM
Analytics	Synapse

Steps:

• Run DMA
• Use DMS for migration
• Cutover (downtime window)
• Optimize performance

MongoDB Migration

Scenario	Target
Compatible API	Cosmos DB (Mongo API)
Large deployment	VM-based MongoDB
Cloud-native	Cosmos DB (SQL API)

Gotchas:

• Partial Mongo compatibility
• Partition key is permanent
• RU cost estimation issues
• Aggregation limitations