[Installing Oracle DataBase Server 11.2.0.3 on Oracle Linux 6.3]: Creating Directory Structure and Setting Necessary Permissions

# mkdir -p /u01/oracle/database/11.2
# chown -R oracle11:dba /u01/oracle
# chmod -R 775 /u01/oracle/database/11.2


# mkdir -p /u01/oraInventory
# chown -R oracle11:oinstall /u01/oraInventory
# chmod -R 775 /u01/oraInventory


# mkdir -p /u02/oradata
# chown -R oracle11:oinstall /u02/oradata
# chmod -R 775 /u02/oradata

# mkdir -p /u03/oradata
# chown -R oracle11:oinstall /u03/oradata
# chmod -R 775 /u03/oradata


# mkdir -p /u03/orabackups
# chown -R oracle11:oinstall /u03/orabackups
# chmod -R 775 /u03/orabackups

I recommend going directly to the latest version of the document, which uses newer software versions

Link to the Oracle installation document.