Oracle 26ai: Out-of-Place Database Patching Explained

Patching a database often means turning it off, which is a problem for businesses. In Oracle 26ai, there is a great new feature called Local Rolling Out-of-Place Patching.

This feature helps you move your database to a new, patched “Oracle Home” on the same server without stopping database (or short downtime). Here is how it works.

First, We install new oracle home dbhome_2

[oracle@myhost01 ~]$ unzip -qd
/u01/app/oracle/product/23.0.0.0/dbhome_2 \
/tmp/LINUX_X64_2326100_db_home.zip
[oracle@myhost01 ~]$ cd /u01/app/oracle/product/23.0.0.0/dbhome_2
[oracle@myhost01 dbhome_2]$ ./runInstaller

we look at our 3-node RAC database. It is currently running on dbhome_1

$ srvctl status database -db testdb
Instance testdb1 is running on node myhost01
Instance testdb2 is running on node myhost02
Instance testdb3 is running on node myhost03

We want to move to dbhome_2 (the patched version). We use a special command with the -localrolling option. Oracle creates new “shadow” instances (like testdb1_4). These are ready to go but are not running yet. This keeps the database safe while we prepare.

[oracle@myhost01 ~]$ srvctl modify database -db testdb \
-oraclehome /u01/app/oracle/product/23.0.0.0/dbhome_2 \
-localrolling
[oracle@myhost01 ~]$ srvctl status database -db testdb
Instance testdb1 is running on node myhost01
Instance testdb1_4 is not running on node myhost01
Instance testdb2 is running on node myhost02
Instance testdb2_5 is not running on node myhost02
Instance testdb3 is running on node myhost03
Instance testdb3_6 is not running on node myhost03

Now, we use the transfer instance command. It moves the database from the old home to the new home.

[oracle@myhost01 ~]$ srvctl transfer instance -db testdb \
-all -drain_timeout 60

Note: The drain_timeout tells Oracle to wait (in this case, 60 seconds) for old users to finish their work before closing the old instance. New users will automatically go to the new patched instance.

If you want you can transfer node one by another, with -node option.

[oracle@myhost01 ~]$ srvctl transfer instance -db orcl \
-node myhost01 -drain_timeout 0

After a few minutes, the transfer is completed. You will see the new instance names are running.

[oracle@myhost01 ~]$ srvctl status database -db testdb
Instance testdb1_4 is running on node myhost01
Instance testdb2_5 is running on node myhost02
Instance testdb3_6 is running on node myhost03

Key for DBAs

• Automation: Oracle handles the creation of unique instance names (appending _#) and the required undo/redo tablespaces automatically.
• Reduced Risk: Because the patching is “out-of-place,” the original Oracle Home remains untouched during the process, providing an easy fallback.
• Seamless Draining: By leveraging srvctl transfer, service availability is maintained, and users are migrated without abrupt disconnections.