10.1.2 and 10.1.3 homes in R12

R12 file system has come up with new model – Code, Data, Configurations are segregated nicely to have easy maintenance, to avert NFS mount issues on shared appl tier configuration systems. Auto-config will not write anything in APPL_TOP, COMMON_TOP area in R12. All instance specific configurations, log files are written in INST_TOP area. Instance Home provides the ability to share Applications and technology stack code among multiple instances.

APPL-TIER

• 10.1.2 C ORACLE_HOME / FORMS ORACLE_HOME (8.0.6 ORACLE HOME equivalence)‏
• 10.1.3 Java ORACLE_HOME/OC4J ORACLE_HOME (iAS ORACLE_HOME equivalence)‏
• INSTANCE_TOP : Each application tier has a unique Instance Home file system associated

Application Server Releases and versions

There are two versions of Oracle Application server 10g (oAS10g) used

• Oracle 10gAS R2: 10.1.2 – 10.1.2.2.0
• Oracle 10gAS R3: 10.1.3.0 – 10.1.3.3
• In R12, 10.1.2 AS and 10.1.3 AS Homes are newly introduced in lieu of 8.0.6 and iAS(1.0.2.2) – 11i Architecture.

Why do we have 10.1.2. AS and 10.1.3 AS? 

• 10.1.2 AS installation will be supporting forms based applications. It is Standalone 10.1.2 forms/reports server installation. Other components are not included.
• 10.1.3 AS tech-stack will be used by java based applications. 10.1.3 AS instance brings latest OC4J code which is successor of 10.1.2 AS. 10.1.3 AS release doesn’t contain forms/reports products.

Hence to take advantage of latest oc4j code 10.1.3 AS got introduced. But to support ebiz forms applications 10.1.2 AS introduced.

 If you dig into the INST_TOP you will find that it only contains all the configuration files, start-stop scripts, log files, certificate files, pid files etc.., so as to make DB_TOP and APPL_TOP untouched for any instance specific changes. So you can also make DB_TOP and APPL_TOP read only.

INSTANCE TOP
Instance home is the top-level directory for an Applications Instance which is known as Instance Home and is denoted the environment variable $INST_TOP. This contains all the config files, log files, SSL certificates etc.

Advantages of new INSTANCE HOME

• The additional Instance Home makes the middle tier more easy to manage and organized since the data is kept separate from the config files.
• The Instance Home also has the ability to share the Applications and Technology stack code across multiple instances.
• Another advantage of the Instance Home is that the Autoconfig writes only in INST_TOP so APPL_TOP and ORACLE_HOME can also be made read only file system if required.
• To create a new instance that shares an existing middle-tier, just create a new instance_top with proper config files and NFS Mount the middle tier

INSTANCE TOP – STRUCTURE

$INST_TOP      : $APPS_BASE/inst/apps/$CONTEXT_NAME/
/admin /scripts :  ADMIN_SCRIPTS_HOME: Find all AD scripts here
/appl              :  APPL_CONFIG_HOME. For standalone envs, this is set to $APPL_TOP
/fnd/12.0.0/secure : FND_SECURE: dbc files here
/admin             : All Env Config files here
/certs               : SSL Certificates go here
/logs                : LOG_HOME: Central log file location. All log files are placed here (except adconfig)
/ora                 : ORA_CONFIG_HOME
/10.1.2             : ‘C’ Oracle home config, Contains tnsnames and forms listener servlet config files
/10.1.3             : Apache & OC4J config home, Apache, OC4J and opmn
                         This is the ‘Java’ oracle home configuration for OPMN, Apache and OC4J
/pids                : Apache/Forms server PID files here
/portal              : Apache’s DocumentRoot folder