AZ-305 Design data storage solutions Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  Use Azure Database Migration Service with online migration

  Why this is correct

  Azure Database Migration Service online mode performs an initial full copy of your schema and data, then continuously replays changes from the source SQL Server transaction log to keep the target Azure SQL database synchronized. This allows you to run the source in production while the subscription catches up, and you can manually cut over with a controlled stop of writes, limiting downtime to minutes. It is specifically designed for large databases like 500 GB because it avoids a single, protracted offline export and uses a scalable staging area in Azure Blob Storage.

• ✗

  Perform offline backup and restore

  Why it's wrong here

  A native SQL Server backup would need to be taken and uploaded to Azure; for Azure SQL Database, you cannot directly restore an on-premises .bak file (that capability is limited to Azure SQL Managed Instance). If you take the database offline to produce a backup and then wait for a 500 GB transfer and restore to finish, the application is down for the entire duration, which is far beyond a minimal downtime window. This method also requires significant storage and network bandwidth, and any incremental changes that occur during the backup can be lost unless you have already handled log tail backups.

• ✗

  Use transactional replication

  Why it's wrong here

  Transactional replication can publish objects from your on-premises SQL Server as a publisher and synchronize them into an Azure SQL database as a subscriber, but it requires you to configure a distributor, manage agents, and carefully handle schema changes, identity columns, and constraints across publishers and subscribers. For a one-time migration of a large database, this introduces ongoing operational complexity and a need to monitor latency and agent failures. A fully managed service like DMS online is designed for exactly this workload, eliminating the replication infrastructure you would otherwise have to build and maintain.

• ✗

  Export BACPAC and import

  Why it's wrong here

  A BACPAC export is a logical schema-and-data bundle produced by the SQL Server Data Tier Application framework, and for a 500 GB database it serializes every table sequentially, making it extremely slow and resource-intensive. Because it captures a point-in-time state, you must either stop writes during export or accept a differential workload afterward, which extends downtime or requires extra reconciliation. It also does not support continuous replication, so this approach is unsuitable for a migration with a strict downtime window.

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