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Azure Database

Azure Database Migration Service: Automate Your Cloud DB Migration

Azure Database Migration Service (DMS) provides fully managed assistance for anyone migrating on-premises databases to Azure database offerings. You can use DMS to migrate any type of database, data type, and migration type. You can also automate the process with PowerShell commandlets.

In this post, we’ll explain Azure DMS service, pricing, service models, migration tools, and show an example of the DMS process. We’ll also show how NetApp Cloud Volumes ONTAP can help ensure that your database remains available and efficient during and after migration.

In this article, you will learn:

What Is Azure Database Migration Service?

Azure Database Migration Service is a fully managed service that enables you to migrate databases or data warehouses from on-premises or other cloud services to Azure. It supports the migration of multiple database types, including SQL Server, Oracle, MySQL, and PostgreSQL.

The service supports homogeneous (SQL Server to SQL Server) and heterogeneous (Oracle to SQL Server) migrations. It enables you to migrate to SQL Database, SQL Server on virtual machines, Cosmos DB, Azure DB for MySQL, or Azure DB for PostgreSQL.

Azure Database Migration Service enables you to easily move data, objects, and schema. It’s resilient and self-healing. It also enables you to automate migration through PowerShell commandlets.  

Incorporated in Database Migration Service is the Data Migration Assistant. This tool enables you to perform a pre-migration assessment to identify any issues that may block migration. It also helps you identify features that may be unsupported or negatively affected. With this assessment you are provided a checklist of preparation steps and a report detailing recommendations for optimization.

Azure Database Migration Service Pricing

Azure Database Migration Service is available in two tiers—Standard and Premium.

The Standard tier is always available for free and supports offline migrations. It is designed for “one-time” migrations and migrations where down time is less of a concern. When you select this tier, you can choose from compute instances with one, two or four vCore CPUs.

The Premium tier is currently available for free for the first six months and then costs $0.37/hour. It supports both off and online migrations and provides access to 4-vCore compute instances. The premium tier is designed for “continuous migrations” and those with business-critical workloads that cannot tolerate downtime.

For additional details and up-to-date pricing you can visit see  the official pricing page.

Azure DMS Service Models

When using Azure Database Migration Service, you can choose from two service tiers—Standard and Premium. The standard tier provides access to up to four virtual cores and enables you to perform offline migrations. It is designed for small to medium workloads.

The premium tier also provides access to four virtual cores and supports both on and offline migrations. It is designed for large and business-critical workloads.

Offline vs online
Offline migrations require creating a copy of your source database and uploading that copy to the target. To ensure a one-to-one copy of your data, this method requires downtime until your target database is ready to support your workloads.  

In comparison, online migration uses a data stream between your source and target database. This enables you to transfer data while caching changes for asynchronous replication. Eventually, your source and target databases are mirrored, and you can shift your workloads over. This method enables you to keep using your database during migration and grants greater flexibility to when you transition workloads.

Azure supports offline migration for most combinations of on-premise and Azure-based databases, but online migration is supported only for several combinations. Please see the full support matrix.

Example of the DMS Process: Migrating SQL Server to Azure SQL Database

Depending on your source and target database, Azure Database Migration Service will require different steps. To give you a basic idea of how this service works the following is a quick walkthrough of a migration from an on-premises SQL Server to Azure SQL Database. This walkthrough is abbreviated from the Microsoft documentation found here

To follow this workflow, you need the following: 

  • SQL Server 2012 or later with the TCP/IP protocol enabled
  • A target database instance in Azure SQL Database
  • Data Migration Assistant v3.3 or later
  • A Microsoft Azure Virtual Network for the Azure Database Migration Service
  • Open inbound communication on ports 443, 53, 9354, 445, 12000
  • Open source and target database access in Windows Firewall

Migration process
Here are the general steps you would take to perform the migration:

1. Assess your on-premise database for any issues that may prevent a successful migration. You can do this via DMA. Once you get your assessment report back, you need to address any issues found before proceeding. You can see a sample report below:

AzureDMSMigrationSource of this and the following images: Azure

2. After you have eliminated any blocking issues, you can migrate your schema using DMA. This requires filling in connection details, selecting which objects to migrate, generating a SQL script, and deploying the script.

3. In the Azure Portal, under Subscriptions, you can register the Microsoft.DataMigration resource provider.

Subscriptions > Resource Providers

4. Next, also via the Azure portal, you should create an Azure Data Migration Service instance. Once created, you can specify your subscription, select or create a virtual network, and choose your pricing tier. 

5. Once your service is created, you can create a migration project within the Database Migration Service console. From here you can provide the source and target server types and the type of migration (on or offline). You also need to specify the source and target details, including connection information and credentials.

 New Migration Project

6. After defining your database details, you can run your migration and monitor its progress until data transfers successfully.

Azure Database Efficiency with Cloud Volumes ONTAP

NetApp Cloud Volumes ONTAP, the leading enterprise-grade storage management solution, delivers secure, proven storage management services on AWS, Azure and Google Cloud. Cloud Volumes ONTAP supports up to a capacity of 368TB, and supports various use cases such as file services, databases, DevOps or any other enterprise workload, with a strong set of features including high availability, data protection, storage efficiencies, Kubernetes integration, and more.

In particular, Cloud Volumes ONTAP helps in addressing database workloads challenges in the cloud, and filling the gap between your cloud-based database capabilities and the public cloud resources it runs on.

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Yifat Perry, Technical Content Manager

Technical Content Manager