Moving from Oracle RDS to Oracle RDS database to shrink storage footprint

Hello,

Can I use TTS to migrate an already existing Oracle RDS database to another Oracle RDS database (same AWS account) using S3?

Currently, you can't migrate data from an RDS for Oracle DB instance using transportable tablespaces. You can only use transportable tablespaces to migrate data to an RDS for Oracle DB instance. Hence, transportable tablespaces cannot be used to reduce the allocated storage on RDS Oracle.

The following document lists the limitation with transportable tablespaces in RDS Oracle:

• Migrating using Oracle transportable tablespaces - Limitations for transportable tablespaces - https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/oracle-migrating-tts.html#oracle-migrating-tts.limitations

I was told by AWS support the only way to shrink the database storage is to use DMS or Datapump to move the database to a "new" copy with less storage allocation.

This is correct. You have the below options available to reduce the size of the RDS database:

Data Pump (Export/Import)

• Importing using Oracle Data Pump - https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Oracle.Procedural.Importing.DataPump.html
• Please note to use EFS for storing the dump files.

AWS DMS (Database Migration Service)

• Getting started with AWS Database Migration Service - https://docs.aws.amazon.com/dms/latest/userguide/CHAP_GettingStarted.html
• Using an Oracle database as a source for AWS DMS - https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Source.Oracle.html

You're correct that Amazon RDS does not allow direct reduction of allocated storage size for Oracle databases, even after you've cleaned up data. This is a limitation of the RDS service design.

Regarding your question about using Transportable Tablespaces (TTS) between RDS instances - no, this is not a viable option for migrating from RDS Oracle database to a new RDS Oracle instance with a smaller storage footprint. This is due to the following limitation: You can't migrate data from an RDS for Oracle DB instance using transportable tablespaces. You can only use transportable tablespaces to migrate data to an RDS for Oracle DB instance.

To reduce your storage footprint, you have below options:

1. Data Pump (Export/Import): While you mentioned having issues with this approach, it remains a standard method. The errors you're encountering might be resolvable with proper configuration.

2. AWS DMS (Database Migration Service): This is another option suggested by AWS Support that could help migrate your data to a new, smaller instance.

For any migration approach, remember to thoroughly test the process, validate the data integrity, and plan for the application cutover to minimize disruption.

Sources
Community | XTTS new feature for RDS | S01 E14 | Lets Talk About Data Show

Limitations for transportable tablespaces