Migrating databases to Azure requires a strategic approach based on source database type, downtime tolerance, and target platform selection. Azure provides several migration solutions to accommodate different scenarios.
For SQL Server migrations, Azure Database Migration Service (DMS) is the recom…Migrating databases to Azure requires a strategic approach based on source database type, downtime tolerance, and target platform selection. Azure provides several migration solutions to accommodate different scenarios.
For SQL Server migrations, Azure Database Migration Service (DMS) is the recommended primary tool. It supports both online (minimal downtime) and offline migrations to Azure SQL Database, Azure SQL Managed Instance, or SQL Server on Azure VMs. DMS handles schema conversion, data migration, and validation seamlessly.
When selecting the target platform, consider these options: Azure SQL Database for fully managed PaaS with automatic updates and scaling; Azure SQL Managed Instance for near 100% compatibility with on-premises SQL Server features; and SQL Server on Azure VMs for lift-and-shift scenarios requiring full OS access.
For heterogeneous migrations from Oracle, MySQL, or PostgreSQL, use Azure DMS combined with the Data Migration Assistant (DMA) for assessment and compatibility analysis. Azure Database for MySQL and Azure Database for PostgreSQL offer native migration tools for their respective platforms.
The migration process should follow these steps: First, assess the current environment using DMA or Azure Migrate to identify compatibility issues and dependencies. Second, remediate any blocking issues discovered during assessment. Third, perform schema migration followed by data migration. Fourth, validate data integrity and application functionality. Finally, execute the cutover during a maintenance window.
For large databases requiring minimal downtime, implement online migration with continuous data synchronization until cutover. Consider using Azure Data Box for initial bulk data transfer when dealing with massive datasets exceeding several terabytes.
Additional recommendations include implementing Azure Private Link for secure connectivity, configuring geo-redundancy for disaster recovery, and establishing monitoring through Azure Monitor. Always perform thorough testing in a non-production environment before production migration, and maintain rollback procedures throughout the process.
Recommend a Solution for Migrating Databases - AZ-305 Complete Guide
Why Database Migration Solutions Matter
Database migration is a critical component of cloud adoption strategies. Organizations moving to Azure need to minimize downtime, ensure data integrity, and choose the most cost-effective migration path. As an Azure Solutions Architect, you must understand various migration approaches to recommend appropriate solutions based on business requirements, technical constraints, and acceptable downtime windows.
What is Database Migration in Azure?
Database migration involves moving data, schema, and database objects from source systems (on-premises or other clouds) to Azure database services. Azure provides several tools and services to facilitate this process:
Azure Database Migration Service (DMS) - A fully managed service designed to enable seamless migrations from multiple database sources to Azure data platforms with minimal downtime.
Azure Migrate - A centralized hub for discovering, assessing, and migrating on-premises servers, databases, and applications.
Data Migration Assistant (DMA) - A standalone tool that helps detect compatibility issues before migration.
SQL Server Migration Assistant (SSMA) - Used for migrating non-SQL Server databases like Oracle, MySQL, and Access to SQL Server or Azure SQL.
How Database Migration Works
Step 1: Assessment Use Azure Migrate or Data Migration Assistant to analyze your current database environment. This identifies compatibility issues, feature parity gaps, and provides sizing recommendations.
Step 2: Choose Target Platform Select the appropriate Azure database service: - Azure SQL Database - Fully managed PaaS, best for modern cloud applications - Azure SQL Managed Instance - Near 100% SQL Server compatibility, ideal for lift-and-shift - SQL Server on Azure VMs - Full control, suitable for legacy applications - Azure Database for MySQL/PostgreSQL/MariaDB - Open-source database migrations - Azure Cosmos DB - For NoSQL workloads
Step 3: Select Migration Method
Offline Migration: Database is taken offline during migration. Simpler but requires planned downtime. Suitable for smaller databases or when downtime is acceptable.
Online Migration: Uses continuous data synchronization to minimize downtime. Source database remains operational during migration. Requires Azure DMS Premium tier.
Step 4: Execute and Validate Perform the migration, validate data integrity, and conduct application testing before cutover.
Key Migration Scenarios and Solutions
SQL Server to Azure SQL Database: - Use DMS for online migrations with minimal downtime - Use BACPAC export/import for smaller databases - Transactional replication for real-time sync requirements
SQL Server to Azure SQL Managed Instance: - Native backup and restore via Azure Blob Storage - Log Replay Service (LRS) for online migrations - DMS for automated online migration
Oracle to Azure: - Use SSMA for schema conversion - Azure DMS for data migration - Consider third-party tools for complex scenarios
MongoDB to Cosmos DB: - Azure DMS supports online migration - Native MongoDB tools with Azure Cosmos DB API for MongoDB
Exam Tips: Answering Questions on Database Migration Solutions
Tip 1: Focus on Downtime Requirements When a question mentions minimal downtime or business continuity, the answer typically involves online migration using Azure DMS. Offline migration is appropriate when downtime windows are acceptable.
Tip 2: Match Source to Target Know which migration tools support which source-target combinations. DMS supports most common scenarios, but SSMA is needed for Oracle, MySQL, and Access to SQL Server conversions.
Tip 3: Consider SQL Managed Instance for Compatibility When questions mention SQL Server Agent jobs, cross-database queries, CLR, or linked servers, Azure SQL Managed Instance is usually the correct target, not Azure SQL Database.
Tip 4: Remember the Assessment Phase Questions about identifying compatibility issues before migration point to Data Migration Assistant or Azure Migrate.
Tip 5: Backup and Restore for Managed Instance Native backup to Azure Blob Storage followed by restore is a simple, cost-effective method for migrating to SQL Managed Instance when some downtime is acceptable.
Tip 6: Cost Considerations DMS Standard tier is free for offline migrations. Premium tier (paid) is required for online migrations with continuous sync.
Tip 7: Size and Complexity Matter Large databases (multi-terabyte) may require physical media transfer using Azure Data Box combined with DMS for delta synchronization.
Tip 8: Read Questions Carefully Look for keywords like heterogeneous (different database engines), homogeneous (same engine), near-zero downtime, or lift-and-shift to determine the best solution.
Common Exam Scenarios
- Company needs to migrate on-premises SQL Server with minimal downtime → Azure DMS online migration - Application uses SQL Server features like SQL Agent → Azure SQL Managed Instance - Simple migration of small database with acceptable downtime → BACPAC or native backup/restore - Oracle database to Azure → SSMA + Azure DMS - Need to assess databases before migration → Azure Migrate + DMA