Minimizing loading on RDS DB instance while running DMS 'full load + cdc' task

Question

Hello all,
I have a currently running RDS db instance (primary) for production and we would like to add a task running 'Fullload + CDC' (or running 'Fullload' or 'CDC' separately) to this instance. However, as I tested, such execution utilized most resources. To prevent this, we are considering establishing a replica of this primary db instance. Yet, replica can perform 'read-only' and fails to run 'cdc'.

Is there any solution to solve the dilemma that we can run 'full load + cdc' (on a replica) while giving the minimized loading to the rds instance?

Many thanks.

Answer

Hi,

you do not mention the type of your source database.

If it is SQL server: DMS supports replication from a read-only replica since v3.4.7. See https://docs.aws.amazon.com/dms/latest/userguide/CHAP_ReleaseNotes.html

```
Support SQL Server read replica as a source	
AWS DMS now supports SQL Server read replica as a source. Using AWS DMS, 
you can now perform live migrations from SQL Server read replica to any AWS 
DMS supported target.
```

All details re. how-to at at https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Source.SQLServer.html

You may also find this post useful: https://aws.amazon.com/blogs/database/migrate-from-a-microsoft-sql-server-alwayson-read-only-replica-to-amazon-aurora-postgresql-with-aws-dms/

Best,

Didier

Answer

Hello Didier

Thank you for your reply. We're using MySQL 5.7 and still trying to achieve the goal.
Many thanks.

Minimizing loading on RDS DB instance while running DMS 'full load + cdc' task

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