Limitations of data migration with Data Migration Assistant and Data Migration Services

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Limitations of data migration with Data Migration Assistant and Data Migration Services

John 101

Hi there, I am trying to create an overview of ways to migrate data(bases) to Azure. I know you can use Data Migration Assistant. I read it's advised to use Data Migration Services for larger migrations and if there is a need and you can't migrate online you could use Data Box.

I saw a lot of information and specs about the different Data Box devices, but I was wondering what the limitations are of Data Migration Assistant and Data Migration services. I want to know when to use DMA or DMS for migrating data(bases).

How much data can they migrate? For example. 100GB, 1TB etc.
How many databases can they migrate?
What security features do they have for during the migration?
What DBMS types can you migrate to Azure?

If you know any relevant info or have links to informational websites please let me know.

Thanks

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Answer 1

Welcome to Microsoft QA.

Question #1

They both can migrate TBs of data but with Data Migration Assistant (DMA) you can spend more than 24 hours to migrate 1 TB. DMA can take 26-28 hours to migrate 700 MB while DMS can do the same in less than an hour, depending on where you are migrating.

Question #2

Data Migration Assistant (DMA) can migrate 8 databases at a time, you can perform assessment of 8 databases in parallel. Data Migration Service many in parallel at the same time and is more resilient. I have witnessed DMS migrating more than 500 databases in parallel, but I don't have knowledge of a documented maximum number of databases that can be migrated in parallel.

Question #3

The assessment these tools take in consideration migration of logins, users and roles on some scenarios. Encrypted objects like stored procedures/functions cannot be migrated using DMA. DMS can migrate databases using Transparent Data Encryption and Always Encrypted. Data is encrypted in transit (TLS encryption is used).

DMA discover and enumerate new security features in the target SQL Server platform that the database can benefit from after an upgrade. DMA can help you migrate users, roles, windows and SQL logins when migrating from SQL Server on-premises to Azure SQL VM. DMA tries to map database users to existent logins on the target database.

DMS provides a security baseline that applies guidance from the Azure Security Benchmark version 2.0 to Azure Database Migration Service. The Azure Security Benchmark provides recommendations on how you can secure your cloud solutions on Azure. The content is grouped by the security controls defined by the Azure Security Benchmark and the related guidance applicable to Azure Database Migration Service.

Question #4

DMA enables you to upgrade to a new version of SQL Server and Azure SQL Database (standalone and Managed Instance). DMS helps you migrate SQL Server, Oracle, MySQL, PostgreSQL, MariaDB, RDS SQL. Mingo DB and PostgreSQL to Azure,

Only DMA can help you migrate (and/or upgrade) SQL Server to SQL Server on Azure VM

John 101 Reputation points

2022-06-15T14:52:39.167+00:00

Thanks a lot for the clear answer, Alberto. I was looking into DMS and was wondering what the difference is between DMS and Azure Migrate. And for my school project I need to be able to automatically setup a secure environment in Azure where the data will be migrated to. I am planning to use Azure Blueprints to do this. I want to setup an SQL server via Azure Blueprints which the database(s) could be migrated to. I suppose it is possible choose the server and resource group it belongs to when using the migration tools of Microsoft.

I have two additional questions:

I know that one of the strategies you can use for migration is database synchronization. I read Azure has a tool called Data Sync, but also read that it is not advised for migrating data. Why does Azure not recommend it? And do you know if Microsoft has a tool for Change Data Capture/Data synchronization from on-premises and Azure databases?

Is it possible to also deploy a single Azure SQL database and a SQL server within a resource group and then take the data from the on-premises database and paste it in the newly deployed database on Azure? Or can I only migrate the whole on-premises database to the Azure SQL server?

*PS: I have not worked with Azure Cloud before so I have limited knowledge about this.

Thanks in advance
Alberto Morillo 34,671 Reputation points MVP Volunteer Moderator

2022-06-15T15:26:28.003+00:00

You can use transactional replication to migrate to Azure SQL also as explained here. You can move data from SQL on premises to Azure SQL Database using Azure Data Factory and Change Data Capture. SQL Data Sync is listed as a migration tool here and for me it can be used as migration tool.

You can create a SQL VM on Azure and an Azure SQL Database on the same resource group and connect them securely using a Private Endpoint. You may want to consider uploading a SQL Server native backup from on-premises to Azure and restore it on the SQL VM to speed up the migration process and take advantage of the private endpoint security.

Hope this helps. Please let me know if you have more questions.

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Limitations of data migration with Data Migration Assistant and Data Migration Services

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