Required Operating System Users and Groups

To install the Oracle Grid Infrastructure software and Oracle RAC, you must create the following operating system groups and users:

The Oracle Inventory group (typically, oinstall) for all installations. The Oracle Inventory group must be the primary group for Oracle software installation owners. Members of the Oracle Inventory group have access to the Oracle Inventory directory. This directory is the central inventory record of all Oracle software installations on a server as well as the installation logs and trace files from each installation.
An Oracle software owner. This is the user account you use when installing the software.

If you want to use a single software owner for all installations, then typically this user has a name like oracle. If you plan to install the Oracle Grid Infrastructure and the Oracle RAC software using separate software owners to separate Grid Infrastructure administrative privileges from Oracle Database administrative privileges, then typically you would use grid for the Oracle Grid Infrastructure software owner and oracle for the Oracle RAC software owner.
The OSDBA group (typically, dba) for Oracle Database authentication

Note: If installing Oracle RAC on Microsoft Windows, OUI automatically creates the ORA_DBA group for authenticating SYSDBA access. Also, if you install the Oracle RAC software while logged in to an account with administrative privileges, you do not need to create a separate user for the installation.

If you want to create separate Oracle software owners so you can use separate users and operating system privileges groups for the different Oracle software installations, then note that each of these users must have the Oracle central inventory group as their primary group. Members of this group have write privileges to the Oracle Inventory directory. In Oracle documentation, this group is represented as oinstall in code examples. A user created to own only the Oracle Grid Infrastructure binaries is called the grid user. This user owns both the Oracle Clusterware and Automatic Storage Management binaries.

Note: You no longer can have separate Oracle Clusterware and ASM installation owners.

If you use one installation owner for both Oracle grid infrastructure and Oracle RAC, then when you want to perform administration tasks, you need to change the value for ORACLE_HOME environment variable to match the instance you want to administer (ASM, in the Grid Infrastructure home, or a database instance in the Oracle home). To change the ORACLE_HOME environment variable, use a command syntax similar to the following example, where /u01/app/grid is the Oracle grid infrastructure home:

ORACLE_HOME=/u01/app/grid; export ORACLE_HOME

If you try to administer an instance using sqlplus, lsnrctl, or asmcmd commands while ORACLE_HOME is set to a different binary path, then you will encounter errors. The Oracle home path does not affect srvctl commands.