It writes the data that you specify to a data file, such as an ASCII file.

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The SQL Server bulk copy feature is an efficient means of copying data from a source database to your DB Instance. Bulk copy writes the data that you specify to a data file, such as an ASCII file. You can then run bulk copy again to write the contents of the file to the destination DB Instance.

Source: http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/SQLServer.Procedural.Importing.html

I have the same idea. A

https://aws.amazon.com/premiumsupport/knowledge-center/rds-import-data/

SQL Server – RDS SQL Server DB instances cannot be created by restoring data from a .BAK file. For details, see Importing and Exporting SQL Server Data. SQL Server tools that can be used for this process include the Generate and Publish Scripts Wizard, SQL Server Import and Export Wizard, and the Bulk Copy (bcp.exe) command-line tool described at Bulk Copy Operations in SQL Server. The following blog post provides additional information about importing data from SQL Server to an RDS DB instance running the SQL Server database engine: How to Migrate SQL Server Database to Amazon RDS Instance.

A
http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/SQLServer.Procedural.Importing.Snapshots.html
Bulk Copy