Oracle Application 12.2.x Dual Filesystem Key features

 In Oracle E-Business Suite (EBS) 12.2, DualFS (short for Dual File System) refers to a feature introduced to support online patching and the zero-downtime patching process. It is used in conjunction with the "online patching" methodology that Oracle introduced starting with 12.2 to enable more efficient patching with minimal disruption to users.

Key Concepts of DualFS in Oracle EBS 12.2:

1. Separation of Run and Patch File Systems:

   • In Oracle EBS 12.2, the Dual File System divides the Oracle E-Business Suite filesystem into two main parts: a "run" file system and a "patch" file system.
   • The run file system contains the currently active version of your applications and is what users interact with.
   • The patch file system contains the patched version of the Oracle Applications files.
   • The two filesystems allow you to apply patches in a dual-phase approach—one for the run system and one for the patch system.

2. Online Patching with DualFS:

   • Oracle 12.2 allows you to apply patches without needing to take the entire system down. While patches are being applied to the patch file system, users can continue using the run file system.
   • The patching process involves copying the patched files into the patch filesystem while the system is live. After patches are applied, the system switches over to the patch filesystem with minimal downtime (essentially, zero-downtime patching).

3. Two Modes of Operation:

   • Run Mode: This is the mode where the system is actively used by end-users, and they interact with the applications.
   • Patch Mode: This is where patches are applied to the "patch" file system. Once patches are successfully applied and validated, the system is switched to use the new patched version.

4. File System Switch (fs_clone):

   • Once the patching is completed on the patch filesystem, a switch is made between the run and patch file systems using the fs_clone utility. The run file system is switched to the patch file system, making it the active environment for users.
   • This switch takes very little time (a few seconds or minutes), and it does not require taking the entire application down, which results in minimal disruption to end-users.

5. Benefits of DualFS:

   • Minimized Downtime: The most significant advantage of DualFS is zero-downtime patching. The system doesn't need to be taken offline for long periods during patch application.
   • Concurrent Patching: Allows patches to be applied concurrently with the normal running of the applications, without disrupting active users.
   • Flexibility in Maintenance: Patching and maintenance can be done during regular business hours, greatly reducing the need for extensive maintenance windows.

6. Patch Lifecycle:

   • When Oracle releases patches, they can be applied incrementally and sequentially. After applying each patch, the system can be validated, and only once all patches are successfully applied can the final switch be made from the patch file system to the run file system.

By utilizing DualFS, Oracle E-Business Suite 12.2 significantly reduces the impact of patching on business operations, enabling enterprises to maintain a more agile and up-to-date system while ensuring continuity of service.