What is the difference between ORACLE_HOME and ORACLE_BASE?

Oracle Database Tips by Donald BurlesonApril 19, 2015

Question: What is the difference between oracle_base and oracle_home environment variables?

Answer: ORACLE_BASE and ORACLE_HOME are directory locations defined by the Oracle Flexible Architecture (OFA) standard. I

ORACLE_BASE - The home directory for the Oracle software (e.g. /u01/app/oracle/product/10.2.1) with subdirectories like:

bin
rdbms
sqlplus
etc.

ORACLE_HOME - Below ORACLE_BASE, the files for each database:

/u01/app/oracle/product/10.2.1/testdb
/u01/app/oracle/product/10.2.1/proddb

In Oracle 11g, the 11g New Features Guide notes important OFA changes, namely the removal of $ORACLE_HOME as an anchor for diagnostic and alert files:

"The database installation process has been redesigned to be based on the ORACLE_BASE environment variable. Until now, setting this variable has been optional and the only required variable has been ORACLE_HOME.

With this feature, ORACLE_BASE is the only required input, and the ORACLE_HOME setting will be derived from ORACLE_BASE."

The Oracle docs note:

ORACLE_BASE - ORACLE_BASE is the root of the Oracle Database directory tree. If you install an OFA-compliant database using Oracle Universal Installer defaults, then ORACLE_BASE is X:\oracle\product\10.2.0 where X is any hard drive.

ORACLE_HOME - ORACLE_HOME corresponds to the environment in which Oracle Database products run. This environment includes the location of installed product files, the PATH variable pointing to the binary files of installed products, registry entries, net service names, and program groups.

If you install an OFA-compliant database, using Oracle Universal Installer defaults, then Oracle home (known as ORACLE_HOME in this guide) is located beneath ORACLE_BASE. It contains subdirectories for Oracle Database software executables and network files.

****************************

If you like Oracle tuning, you might enjoy my book "Oracle Tuning: The Definitive Reference", with 950 pages of tuning tips and scripts.

You can buy it direct from the publisher for 30%-off and get instant access to the code depot of Oracle tuning scripts.

��