Shared application tier in R12

Shared Application Tier File System

We can configure multiple application node machines working with a single E-Business Suite database node. This creation of a “multi-node” E-Business Suite instance is frequently done to lower cost of ownership (many small machines are cheaper than one big one), increase fault tolerance (one machine fails, others do not), or scale the instance (support more users and a greater load).

When configuring Oracle E-Business Suite to use a shared application tier file system, the application tier node can be configured to perform any of the standard application tier services, such as Forms, Web, and Concurrent Processing (Batch).
Note the following definitions:

Node
A node/server/instance is a logical set of processes running on one hardware machine. In a single-node installation of Oracle E-Business Suite, all the Applications processes (including the database processes) run on one node, whereas in a multi-node installation, the processes are distributed across multiple nodes.
A multi-node installation of Release 12 supports both shared and non-shared application tier file systems. An application tier file system consists of:

• APPL_TOP file system (APPL_TOP and COMMON_TOP directories).
• Application tier technology stack file system (OracleAS 10.1.2 and 10.1.3 Oracle Homes).
• Instance Home (INST_TOP) file system. Each application tier has a unique Instance Home file system associated with it.

Service

A service is a functional set of Oracle E-Business Suite application processes running on one or more nodes. Where applicable, the term ’service’ is replacing the more traditional term of ’server’.

Application Tier Services

The following are the major application tier services:

• Root services
• Web Entry Point services
• Web Application services
• Batch Processing services
• Other services

So if you have two nodes,one will serve as Primary Node and other will serve as Secondry Node. You can configure both the Application tier node as follows:

Primary Application Tier Node

A primary application tier node is the first application tier node where the APPL_TOP, COMMON_TOP, OracleAS 10.1.2 Oracle Home and OracleAS 10.1.3 Oracle Home are installed and configured.

Secondary Application Tier Node

A secondary application tier node is an application tier node where APPL_TOP, COMMON_TOP, 10.1.2 Oracle Home and 10.1.3 Oracle Home are visible and configured. The APPL_TOP, COMMON_TOP, OracleAS 10.1.2 Oracle Home and OracleAS 10.1.3 Oracle Home file system is mounted to this node from the primary application tier node, or from an NFS server.
Instance Home

Note :  In a shared file system, each application tier will have a unique Instance Home, which should be located on the local file system.

Shared Application Tier File System Architecture
In a shared file system, all application tier files (with the specific exception of the Instance Home file system) are installed on a shared disk resource, which is mounted on each application tier node. Any application tier node can be configured to perform any of the standard application tier services, such as Forms, Web and Concurrent Processing (Batch) services. All changes made to the shared file system are immediately accessible to all application tier nodes.

Shared Application Tier File System Layout
When configuring Oracle E-Business Suite to use a shared application tier file system, an application tier node can be configured to perform any of the standard application tier services, such as Forms, Web, or Concurrent Processing (Batch) services. An application tier will have a unique Instance Home associated with it that cannot be shared with other application tiers. You can configure the services running on an application tier node to match the node’s intended role

Example Shared File System

The following is an example of mount points shared on each application tier node:

• COMMON_TOP: /ebiz/oracle/VIS/apps/apps_st/comn
• APPL_TOP: /ebiz/oracle/VIS/apps/apps_st/appl
• OracleAS 10.1.2 ORACLE_HOME: /ebiz/oracle/VIS/apps/tech_st/10.1.2
• OracleAS 10.1.3 ORACLE_HOME: /ebiz/oracle/VIS/apps/tech_st/10.1.3

In the figure shown below, entitled “Shared Application Tier File System”, Server-appl_node1 is the primary application tier node, and uses the file systems “/ebiz/oracle/VIS” and “/ebiz/oracle/inst”. The file system “/ebiz/oracle/inst” contains the Instance Home, and “/ ebiz/oracle/VIS ” contains the APPL_TOP, COMMON_TOP, OracleAS 10.1.2 and 10.1.3 Oracle Home.

Server-appl_node2 is the secondary application tier node, and the shared file system “/ebiz/oracle/VIS” is also mounted on this node. The file systems “/ebiz/oracle/inst/apps/VIS_appl_node1″ and “/ebiz/oracle/inst/apps/VIS_appl_node2″ are only visible on the respective nodes.