Local Rolling Database Maintenance. Starting with Oracle Database 23ai, you can apply rolling patches locally for Oracle Real Application Clusters and Oracle RAC One Node deployment. It’s very similar to single-server rolling database maintenance, but this feature is used for the multinode RAC environment. So let’s take a look at how it works.
So let’s assume a two-node RAC database example. So we have host A and host B, and CDB1 instance running out of host A, CDC2 instance running out of host B. When we perform our place patching, we install the software in a new home and then we apply patch.
Once patch operation is complete with the local rolling database maintenance, we can start new home from a new instance out of a new home, while the original instance is still running out of original home. So at one point, on host A, we’re going to have two instances, one from original home and the other instance out of a new home.
Once everything is ready, services and instances, the services and sessions are moved to new instance running out of a new home. And once the sessions are moved, then the original instance is stopped.
And same thing happened on host B. So we install the new version of the software or we install or patch the software in a new home and then start a new instance out of a new home, in this example, CDB2/4. And then sessions are moved to new home, the original instance is stopped.
Local database maintenance provides uninterrupted database availability during maintenance activities such as patching for Oracle RAC and Oracle RAC One Node databases. This significantly improves the availability of your databases without causing extra workload on other cluster nodes. So let’s take a look at examples.
First, you download Oracle Database installation image file and extract the image file into new Oracle home directory. And from the new Oracle home directory, start OUI and apply required release update. And then perform software installation. So it is installing the patched software in a new home.
And then we’re going to run SRVCTL modify database command with a -localrolling option. This is to enable local rolling to create a new rec instance. So as soon as you run this command, new instances are created but stopped. For example, if you have a two-node rec database in the first node, the new instance is created but stopped. In the second node, a new instance is created but stopped.
And then we’re going to transfer Oracle RAC and Oracle RAC One Node database and PDBs and services from the old Oracle home to the new Oracle home. And this is the step to start the instances out of a new home and then transfer services, the PDBs, the services to new instances and then stop original instances and that’s by SRVCTL transfer instance.
And now you’re going to verify database configuration changes. And the output of a server control configure database command, it should show new instance names for the database.
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