Complete preupgrade tasks and checks to assist you with completing a successful upgrade.
This chapter provides information and procedures for the pre-upgrade tasks, including planning your upgrades, data-gathering, testing, installing the new Oracle software for the upgrade, using the Parallel Upgrade Utility to carry out your upgrade, and performing other checks and tasks.
About Configuring an Oracle Home in Read-Only Mode
Starting with Oracle Database 18c, you can configure an Oracle home in read-only mode. A read-only Oracle home prevents creation as well as modification of files inside the Oracle home directory
ORACLE_HOME. A read-only Oracle home can be used as a software image for simplifying patching and mass rollout of software across multiple database servers.
You can configure an Oracle home in read-only mode after you have installed the Oracle database in the software-only mode, but before creating the listener and the database.
A traditional read-write Oracle home contains instance-specific files. However, when the Oracle home is read-only, instance-specific files are stored separately in the Oracle base directory
ORACLE_BASE. Therefore, a read-only Oracle home can be used as a software image that can be shared across multiple database servers, as it stores only the static files. This simplifies patching and mass rollout as only one Oracle home image needs to be updated to distribute a patch to multiple database servers.
Apart from the traditional
ORACLE_HOME directories, the following additional directories exist in a read-only Oracle home:
ORACLE_BASE_HOME: This is a subdirectory within the
ORACLE_BASEdirectory. This directory contains user-specific files, instance-specific files, and log files.
ORACLE_BASE_CONFIG: This directory is same as the
ORACLE_BASEdirectory. This directory contains instance-specific dynamic files, such as configuration files.
Section “Configuring Read-Only Oracle Homes” in the Oracle Database installation guide specific to your platform for more information about configuring an Oracle home in read-only mode.