AZ-305 Question 198
Single answerYou are migrating a set of high-transaction Microsoft SQL Server databases from your on-premises data center to Azure SQL Database. The business requires minimal downtime and a repeatable process to accommodate future database migrations as well. Which approach should you recommend to achieve these requirements?
- A
Use Azure Database Migration Service in offline mode to perform a one-time operation.
- B
Use Azure Database Migration Service in online mode to continuously replicate data before cutover.
- C
Perform a manual backup and restore of the database files to Azure Storage, then import them into Azure SQL Database.
- D
Export the databases to BACPAC files and use Azure Data Factory to load the data into Azure SQL Database.
Show answer and explanation
Correct answer: B
Explanation
When designing migrations that require minimal downtime, leveraging Azure Database Migration Service in online mode is a best practice according to Microsoft documentation (https://learn.microsoft.com/azure/dms/). This method keeps databases operational while data is replicated to the cloud. Once synchronization catches up, you can schedule a brief cutover period, resulting in a short outage and satisfying strict SLAs.
- A. Incorrect.
Option 1 is incorrect. Although the offline mode can work for smaller, less critical databases, it requires a full downtime window while data is migrated. This does not meet the requirement for minimal downtime.
- B. Correct.
Option 2 is correct. Azure Database Migration Service in online mode provides continuous replication from the source SQL Server to Azure SQL Database. You can synchronize changes while the original database remains online, and then switch over with minimal outage.
- C. Incorrect.
Option 3 is incorrect. While manual backup and restore can migrate the databases, it lacks the continuous replication needed for minimal downtime. You would have to stop transactions, back up, transfer, and restore, resulting in a larger downtime window.
- D. Incorrect.
Option 4 is incorrect. Exporting to BACPAC and using Azure Data Factory is more manual and typically involves downtime when exporting and importing. It may be feasible for small databases but does not easily support continuous replication for minimal planned downtime.