How to Migrate On-Prem to Azure — A Field Runbook

🧭 Overview

This field runbook distills lessons from multiple enterprise Azure migrations I’ve led — from hybrid datacenters to full cloud adoption across manufacturing, fintech, and religious organizations. It’s written for real-world engineers, not theory: what actually works when you’re connecting on-prem infrastructure to Azure at scale.

⚙️ 1) Plan the Landing Zone

Define the foundation before moving workloads.

Create Management Groups for governance tiers (Corp / Prod / Dev).
Enable Azure Policy for cost limits, resource naming, and security baselines.
Design a Resource Group strategy by function or application.
Turn on Defender for Cloud and Azure Monitor from day one.

🧩 2) Identity & Access

Sync on-prem Active Directory with Entra ID (Azure AD Connect or Cloud Sync).
Enable MFA and Conditional Access for administrators.
Use Privileged Identity Management (PIM) for Just-In-Time access.
Protect secrets in Key Vault with access policies and logging.

🌐 3) Networking & Connectivity

Build Virtual Networks (VNETs) for each environment (Prod, Test, Dev).
Create subnets for tiered app layers (front end / app / data).
Configure NSGs (Network Security Groups) and UDRs (User-Defined Routes).
Establish Site-to-Site VPN for initial connectivity.
For stable enterprise links, provision ExpressRoute — with firewall terminations on both ends.

🧱 4) Storage & Data Migration

Migrate file shares via Azure File Sync or AzCopy.
Use Azure Migrate for VM discovery and replication.
For databases, replicate to Azure SQL Managed Instance or SQL DB with minimal downtime.
Apply Storage Lifecycle Management for cold tiers and archive.

🖥️ 5) Compute & VMs

Use Azure Migrate to assess readiness scores and right-size VM SKUs.
Deploy VMs to availability zones and enable auto-shutdown policies.
For scalable apps, use VM Scale Sets or App Service Plans.
Modernize legacy VMs into containers or Functions when possible.

🔐 6) Security Posture

Enable Defender for Servers and Endpoints.
Apply zero-trust principles at every layer.
Use Azure Firewall or 3rd-party NVA for east-west and north-south traffic inspection.
Monitor with Sentinel (SIEM/SOAR) connected to Log Analytics.

📈 7) Monitoring & Observability

Centralize logs in Log Analytics Workspace.
Set alert rules for CPU, memory, latency, and availability.
Deploy Application Insights for performance tracking.
Integrate with Teams or email for critical alerts.

💾 8) Backup & Disaster Recovery

Use Azure Backup Vault for VMs and SQL instances.
Configure Geo-redundant storage (GRS).
Test restore operations quarterly.
Implement Azure Site Recovery (ASR) for cross-region failover.

💡 9) Governance & Cost Optimization

Enforce tags (owner, cost center, env).
Use Cost Management + Budgets for alerts.
Apply Azure Advisor recommendations for rightsizing.
Archive or deallocate unused resources.

🔄 10) Cutover Strategy

Perform final syncs using Azure Migrate replication.
Validate DNS, connectivity, and security rules.
Schedule cutover during low traffic windows.
Monitor telemetry immediately post-cutover for stability.

🧰 Tools & References

Azure Migrate – Workload discovery and replication.
Storage Explorer – File transfer and validation.
Azure Arc – Hybrid management for on-prem resources.
Bicep / Terraform – Infrastructure as Code for repeatability.
Microsoft Cloud Adoption Framework – Best practice guide.

🔗 Cross-Reference

Also see: How to Migrate On-Prem to Azure — A Field Runbook for the Microsoft implementation pattern.