A while ago, Mike and I were testing upgrades on Exadata on a system that we had borrowed for a short period of time. Now, they (the owners) haven’t reclaimed the Exadata DB System yet. Some times I wonder whether they forgot all about it – and I won’t tell them because I like the idea of my very own Exadata playground. I decided to try out a migration using Zero Downtime Migration (ZDM) to an Exadata DB System (ExaCS).
Prepare source environment
There are no changes to the way that you prepare your source environment. Just follow the same procedure as described in a previous blog post.
The source database can run on any Linux platform – a regular one or an Exadata. It doesn’t matter. ZDM will take care of the details for you.
Prepare 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 you can use ZDM to make all the changes for you; simple and easy.
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.
The other parameters doesn’t matter – the database gets overwritten anyway by ZDM. When using the OCI webpage to create a new database on an Exadata DB System you can’t specify exactly which Release Update to use. You will get the same patch level as the DB System Version. So you might end up having to apply a patch to the DB System – or use another tool to create the database. 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 or specifying an exact Release Update of the Oracle Home, 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.
How To Migrate
When your target database is a RAC database ZDM needs to connect to only one of the nodes in the cluster. It doesn’t matter which node you choose, as long as ZDM can connect to that node. And, obviously, be sure to specify that node in the
targetnode parameter of the
zdmcli migrate database command.
To perform the actual migration you can just follow the procedure I described in a previous blog post. That’s really all there is to it.
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.