Zero Downtime Migration – Physical Online Migration to ExaCS

This will be an easy blog post. To migrate your Oracle Database to Exadata DB System (ExaCS), just follow this procedure from the DBCS blog post. Plus, execute these two commands on the target after the migration:

[root@tgthost]$ dbaascli registerdb prereqs --dbname [db_name] --db_unique_name [db_unique_name]
[root@tgthost]$ dbaascli registerdb begin --dbname [db_name] --db_unique_name [db_unique_name]

More Details, Please

Granted – the above statement is bold and it is almost true. There are a few important details to share. First, have a look at Additional Information for Migrating to Exadata Cloud Service which you find the Release Notes

Target Environment

To get the full benefits of Exadata you should be running RAC databases. Exadata and RAC is a perfect match but it is up to you to decide. If your source database is already a RAC database (or RAC One Node) you must migrate to a RAC database. However, if your source database is a single instance you have to option to either stay single instance or go RAC. If you go RAC, just create the target placeholder database as a RAC database, and everything else will happen automatically.

You must create a placeholder database on the target system. The placeholder database gets overwritten ZDM during the migration but it is initially used by ZDM to get information on how you want to configure your target database in OCI. For example, the migrated database will be placed in the same Oracle Home as the target placeholder database. Also, the architecture is determined this way. In other words, if you create the target placeholder database as a RAC database; then your source database is automatically converted to a RAC database during migration. If you create a single instance placeholder database; you get a single instance database.

Just like any other migration, when creating the placeholder database there are some things you should be aware of. On the OCI webpage you have to:

  • Set Database name to the DB_NAME of the source database.
  • Set Database version to the same as the source database.
  • Ensure the patch level of the Oracle Home match that of the source system – or be higher.
  • Ensure that the Password matches the SYS password of the source database.

When using Zero Downtime Migration (ZDM) to migrate to Exadata DB System (ExaCS) be sure to create the target placeholder database in the correct manner.

You can choose your own DB_UNIQUE_NAME – it should differ from the source database. Select an Oracle Home that has the same or higher patch level than your source database. I recommend to always migrate to the latest Release Update. If necessary, ZDM will automatically invoke datapatch after the switchover. The other parameters don’t matter – the database gets overwritten anyway by ZDM. Also, be aware when using the OCI webpage you get a RAC database. There is no option to change it. But it is after all the perfect match for Exadata anyway.

Now, if you want more advanced options – like creating a single instance database, you can’t use the OCI webpage. You will have to use either dbaaspi or dbaascli. That gives you full control over the options – but they are not as easy to use as the webpage.

It’s A Wrap

I have created a video on YouTube that demos a migration to Exadata DB System.

Speaking of YouTube, I suggest that you subscribe to the Oracle Database Upgrades and Migrations YouTube channel so you never miss anything.

The Exadata Cloud Service is an awesome platform and it is really easy to migrate to it using Zero Downtime Migration. And converting to RAC is even easier.

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