Migrate to Azure SQL Managed Instance

Step 1: Assess Your Source Environment

This is a critical first step. You need to understand your current SQL Server environment to identify any potential blockers or areas requiring attention before migrating.

Tools for Assessment:

• Azure Data Migration Assistant (DMA): Analyzes your on-premises SQL Server databases to identify compatibility issues with Azure SQL Managed Instance. It also provides recommendations for performance improvements.
• Azure Migrate: A centralized service for discovering, assessing, and migrating on-premises servers, applications, and databases to Azure. It can orchestrate the migration of SQL Server instances.
• PowerShell/SQL Server Management Studio (SSMS): For manual checks of database compatibility, server configurations, and features used.

Key Assessment Areas:

• SQL Server version and edition.
• Features used (e.g., CLR, Service Broker, cross-database queries).
• Database compatibility levels.
• Login and SQL Agent job analysis.
• Performance metrics and resource utilization.

Step 2: Prepare Your Target Azure SQL Managed Instance

Set up your Azure SQL Managed Instance environment to receive the migrated databases.

Creating an Azure SQL Managed Instance:

1. Navigate to the Azure portal.
2. Search for "Azure SQL Managed Instance" and click "Create".
3. Configure the instance details:
• Subscription and Resource Group: Select your desired subscription and resource group.
• Managed instance name: A unique name for your instance.
• Region: Choose a region close to your users or applications.
• Compute + Storage: Select the appropriate service tier (General Purpose or Business Critical), vCores, and storage size based on your assessment.
• Virtual network: Create a new virtual network or use an existing one. This is crucial for network connectivity.
• Subnet: Ensure the subnet is dedicated and has a sufficient IP address space.
• Authentication: Configure SQL authentication or Azure Active Directory authentication.
4. Review and create the instance. Deployment can take a significant amount of time (often several hours).

Network Configuration:

Ensure your virtual network is properly configured for connectivity with your source environment. This typically involves:

• Setting up a VPN Gateway or ExpressRoute connection.
• Configuring Network Security Groups (NSGs) and route tables to allow traffic between your source and the Managed Instance subnet.

Step 3: Choose a Migration Method

Azure SQL Managed Instance supports several migration methods, each suited for different scenarios.

Recommended Migration Methods:

• Azure Database Migration Service (DMS): A fully managed service that enables seamless migrations from multiple database sources to Azure data platforms with minimal downtime. This is often the preferred method for online migrations.
• Transactional Replication: You can configure transactional replication from your source SQL Server to Azure SQL Managed Instance for near-zero downtime migrations.
• Backup and Restore: For offline migrations or smaller databases, you can take a full backup of your database and restore it to Azure SQL Managed Instance. This requires downloading the backup to a URL or blob storage accessible by Azure.
• Azure Data Factory (ADF): Can be used for migrating schema and data, especially in scenarios where complex transformations are required.

Factors to Consider:

• Downtime tolerance: Online migrations (DMS, replication) minimize downtime, while offline methods require scheduled downtime.
• Database size: Larger databases may benefit from more efficient transfer methods.
• Complexity of the workload: Applications with high transaction rates might require online migration.
• Network bandwidth: Affects the speed of data transfer.
• Your expertise: Some methods are more complex to set up than others.

Step 4: Perform the Migration

This step involves executing the chosen migration method.

Using Azure Database Migration Service (DMS) - Online Migration Example:

1. Create a DMS instance: In the Azure portal, create an Azure Database Migration Service instance.
2. Create a migration project: Select "SQL Server" as the source and "Azure SQL Managed Instance" as the target. Choose "Online data migration".
3. Configure source and target details: Provide connection strings for your source SQL Server and target Azure SQL Managed Instance.
4. Map databases: Select the databases you want to migrate.
5. Configure migration settings: Specify the Azure Blob Storage account to be used for intermediary backups.
6. Run the migration: Start the migration process. DMS will first perform a full load and then continuously synchronize changes.
7. Monitor progress: Track the migration status in the DMS portal.

Using Backup and Restore (Offline Migration Example):

1. Take a full backup: Back up your source database to a `.bak` file.
2. Upload to Azure Blob Storage: Upload the `.bak` file to an Azure Blob Storage container.
3. Grant access: Ensure your Azure SQL Managed Instance has read permissions to the Blob Storage container (e.g., via Shared Access Signature or Service Principal).
4. Restore to Managed Instance: Use T-SQL commands from SSMS connected to your Managed Instance to restore the database from the Blob Storage URL.

RESTORE DATABASE YourDatabaseName
FROM URL = 'https://yourstorageaccount.blob.core.windows.net/yourcontainer/yourdatabase.bak'
WITH MOVE 'YourLogicalDataFileName' TO 'ms-sql://yourmi.yourdomain.database.windows.net/YourDatabaseName/YourLogicalDataFileName.mdf',
MOVE 'YourLogicalLogFileName' TO 'ms-sql://yourmi.yourdomain.database.windows.net/YourDatabaseName/YourLogicalLogFileName.ldf';

Step 5: Cutover and Validation

This is the final step where you switch your applications to the new Azure SQL Managed Instance and verify its functionality.

Performing the Cutover:

The cutover process depends on your migration method:

• Online Migrations (DMS/Replication):
  • Stop all incoming transactions to the source database.
  • Wait for DMS to apply any remaining pending changes.
  • Initiate the cutover in the DMS portal.
  • Update your application connection strings to point to the Azure SQL Managed Instance.
• Offline Migrations (Backup/Restore):
  • Once the database is restored, update your application connection strings.

Validation:

After cutover, perform thorough validation:

• Application functionality: Test all critical application features.
• Data integrity: Run queries to compare data between source and target (if possible and applicable).
• Performance: Monitor application performance and query execution times.
• Login and permissions: Verify all necessary logins and permissions are correctly migrated or recreated.
• SQL Agent Jobs: Ensure any migrated SQL Agent jobs are running as expected.

Step 6: Post-Migration Optimization

After a successful migration, focus on optimizing your Azure SQL Managed Instance for performance, cost, and security.

Optimization Tasks:

• Performance Tuning:
  • Analyze query performance using tools like Query Store and Automatic Tuning.
  • Adjust service tier and hardware configuration if needed.
  • Update statistics and rebuild indexes.
• Cost Management:
  • Consider Reserved Instances for cost savings on predictable workloads.
  • Monitor resource utilization to right-size your instance.
• Security Enhancements:
  • Implement Azure security best practices (e.g., Azure Defender for SQL, firewall rules, vulnerability assessment).
  • Review and refine Azure Active Directory integration.
• Monitoring and Alerting:
  • Set up Azure Monitor alerts for key performance metrics and potential issues.
  • Configure diagnostic logs for auditing and troubleshooting.
• Backup and Disaster Recovery:
  • Configure long-term retention policies for backups if required.
  • Explore options for high availability and disaster recovery (e.g., Geo-Replication).