Starting with Oracle Database 18c, you can configure an Oracle home in read-only mode.
In a read-only Oracle home, all the configuration data and log files reside outside of the read-only Oracle home. This feature allows you to use the read-only Oracle home as a software image that can be distributed across multiple servers.
Apart from the traditional ORACLE_BASE and ORACLE_HOME directories, the following directories contain files that used to be in ORACLE_HOME:
Benefits of a Read-Only Oracle Home
Enables seamless patching and updating of Oracle databases without extended downtime.
Simplifies patching and mass rollout as only one image needs to be updated to distribute a patch to many servers.
Simplifies provisioning by implementing separation of installation and configuration.
Note:This feature does not affect how database administrators monitor, diagnose, and tune their system performance.