We are planning to move our main database to the Azure SQL database. The DB provides a 24/7 highly OLTP application (financial / credit card) with a latency of some transactions that becomes less than 50 ms. The size of the database is around 8 TB with a couple of tables of 1 TB mostly that are mostly insert. We want to migrate with the minimum possible downtime.
Reading the documents on how to do the migration online, there is data migration service (DMS) and replication. I'm not sure if moving forward with DMS (in preview) is the best way to migrate large databases online.
Questions We will be testing these scenarios, but we wanted to know if someone has experience with that.
- We are concerned about the impact that initial synchronization would have for both DMS and replication.
- If we go with replication, since the subscriber is a blue SQL DB, we have to synchronize from the snapshot. What is the impact? Is it possible to synchronize a 7 TB database with a pair of 1 TB tables using snapshots without causing a major impact on the current OLTP system?
- Since we can also synchronize from the backup, what we have done in the past, and we know that the backups do not have a big impact on the system, we were thinking about creating a new subscriber that is synchronized from the backup and then use DMS on that new subscriber to migrate to Azure SQL DB. Is this a better option?