Migrate MySQL 8 to Aurora MySQL 8

Question

We are having trouble migrating on-premise MySQL 8.0.26 to AWS Aurora MySQL. For this project we're using AWS Database Migration Service (DMS) but it seems we are reaching the limit of the amount of databases to migrate. When we try to migrate over 500+ databases with one task, the task fails with the error "No tables were found at task initialization". When we edit the filter to migrate < 500 databases, the task starts successfully. Can anyone confirm that 500 databases is the limit for DMS? We have to do over 7k databases, but filtering those will not be easy. Is it possible to increase the current limit of 500? Kind regards, Lennard.

Answer

You can find limits for DMS here: https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Limits.html

Multiple tasks will be a better path for you as you also may be hitting some limits of the migration instance.

Answer

I dont think there is a limit on databases or schemas to migrate for mysql source.
I would suggest enable extra logging (DETAILED_DEBUG) on component SOURCE_UNLOAD and track the query being passed by DMS against  source to capture table list. 
once you have the query from log use that directly on source db to identify any issues. this could be an edge case or a bug. once identified i would suggest working with AWS Support for solution/bug reporting/workaround.

Migrate MySQL 8 to Aurora MySQL 8

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