Oracle DB Migration - Azure to AWS RDS

Question

We have Oracle 12c DB Server on Azure which we want to migrate to AWS RDS Oracle 19c.
DB Size is around 6 TB  and we can't afford downtime so can anyone please suggest best approach to achieve this ?

Accepted Answer

Hello hc,
given the size of your DB, the 19c upgrade you'd like to do and the fact that you cannot afford downtime, your migration path basically narrows down to **replication**.
Aside from 3rd-party solutions (e.g., Oracle GoldenGate or Quest Shareplex), AWS offers the "[Database Migration Service (DMS)](https://aws.amazon.com/dms/)" for that.
The basic workflow in either case is:

1. Prepare source and target database for access by the replication tool
2. Do a full load of the data from source to target.
3. Run a continuous change data capture to keep up with changes on the source.
4. Stop applications from changing the source, let the replication tool finish the sync and switch over to your target.

Which tool should you choose? That depends on mainly 2 factors:

* **Price**: 
  * If your organization already has licenses for 3rd-party replication tools, you'd probably go for that. Additionally, there will likely be staff with experience in using these tools, then.
  * DMS itself is free of charge; costs will arise only for the underlying infrastructure until you stop or delete it.
* **Limitations:** While an Oracle-to-Oracle replication is a simpler use case than a platform change, each tool still has its own limitations (e.g., extended data types not replicatable). For DMS, see "[Limitations on Oracle as a source](https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Source.Oracle.html#CHAP_Source.Oracle.Limitations)" and check if any of these affect you and whether other solutions don't have these particular limitations.

If you need further info, let me know in the comments; otherwise I'd appreciate if you mark my answer as "accepted".

Kind regards, Uwe

Answer

Hi Hc

From the note I understand you have Oracle 12c DB Server on Azure which you want to migrate to AWS RDS Oracle 19c. DB Size is around 6 TB and you can't afford downtime.

You can use either use AWS DMS or Native Oracle tools to preform this migration.  For large database you must ensure that the network between the two cloud environments is optimized depending on network speed, you can use an EC2 as an intermediary or use AWS SnowBall. You will need to configure replication between the two clouds, monitor and optimize for low latency.

Please note When a major version upgrade is invoked on the console, AWS CLI, or Amazon RDS API, the automation completes the following steps:
1.Take a pre-upgrade snapshot (if configured for backups). You can use this snapshot to roll back to the previous engine version if needed.
2.Shut down the instance and prepare it for the upgrade.
3.Run Oracle upgrade scripts.
4.Take a post-upgrade snapshot.

I hope this helps.

References:

==========

1.https://docs.aws.amazon.com/prescriptive-guidance/latest/patterns/migrate-an-on-premises-oracle-database-to-amazon-rds-for-oracle.html#migrate-an-on-premises-oracle-database-to-amazon-rds-for-oracle-tools

2.https://aws.amazon.com/getting-started/hands-on/move-to-managed/migrate-oracle-to-amazon-rds/

Oracle DB Migration - Azure to AWS RDS

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