Overview of R12 Shared Applicaton File System

In this post I am going to discuss about Shared Application File System.

A multi-node installation of Release 12 supports both shared and non-shared application tier file systems.Without a shared application tier file system each application tier node has its own file system,which must be managed independently.

In Shared Application File system,a Single Application Tier file system that can be accessed simultaneously from more than one machine. The application tier file system disk is attached to a mount point of the same name on all machines.

Any Application 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.

Each node has its own environment file (i.e, APPSCONTEXT_NAME.env) and application context file (i.e, CONTEXT_NAME.xml).

Special Note:

- Use a local file system for the Instance Home for optimum performance.
- All Application tier nodes must be running the same operating system.
- The value for the context variable "s_atName" must be same across all the application tier nodes context files.
- User ID and group ID should be consistent across all nodes to avoid file access permission issues


Advantage of Shared Application File System

- Distributed AD help in reducing the downtime by improving the efficiency of patch application.
- You can adminstrate tasks from any one node.
- Reduction in Requirment of Disk Space
- Increase system availability and additonal requirments by adding machines into existing system.

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.


Major Application Tier Services:

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

Below is an example of Multi-Node installation:

A)Primary Application Tier-Node

Note:Installed and Configured Services
- APPL_TOP
- COMMON_TOP
- OracleAS 10.1.2 ORACLE_HOME
- OracleAS 10.1.3 ORACLE_HOME

B)Secondary Application Tier-Node

Note:Visible and Configured Services

- APPL_TOP
- COMMON_TOP
- OracleAS 10.1.2 ORACLE_HOME
- OracleAS 10.1.3 ORACLE_HOME

The above services are mounted to secondary node from Primary application tier node or from an NFS Server.

c) Instance Home

Note: Top-level directory that contains instance-specific files associated with an Application Tier.

- APPL_TOP
- COMMON_TOP
- OracleAS 10.1.2 ORACLE_HOME
- OracleAS 10.1.3 ORACLE_HOME
- log files
- pid files
- certificates files

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