E-Business Suite R12.2: Online Patching

Oracle E-Business Suite Release 12.2 introduces Online Patching, a new feature that greatly reduces the downtime that was needed in previous releases for application of Release Update Packs (RUPs), Critical Patch Updates (CPUs), and other patches and bug fixes of various kinds.

How it Works?

1. A copy is made of the running system.
2. Patches are applied to the copy while users continue to access the running system.
3. Transparently to users, the copy becomes the new running system.
4. What was the original running system (now obsolete) is deleted. 

The Online Patching infrastructure is the Oracle E-Business Suite Release 12.2 mechanism that allows Oracle E-Business Suite patches to be applied online, while the system is running and users are working as normal. This infrastructure includes database objects and file system components.
To Incorporate the Online patching There few Architectural Changes in 12.2 to Support Online Patching.

Patching Occurs on a Copy Not on the Actual system.

• Database
• A separate copy is maintained of all database code objects that
  are changed by a patch
• File system
• All patches are applied to the secondary file system
• Synchronization of the file systems is managed by the patching tools

DataBase 11G R2 Edition-Based Redefinition (EBR)
Enables the online upgrade of the database tier,Allows an application to efficiently store multiple copies of its application definition in the same database. Provides an isolation mechanism that allows pre-upgrade and post-upgrade schema to co-exist,Changes to database objects are made in the isolation of an “Edition” ,Changes to database objects do not effect the running Application.

Database Editions

• Run Edition
• The edition currently in use by the running application ,Used by Online Users
• This is always the default database edition 
• Never changed by a Patch
• Patch Edition
• The edition currently in use by the patching tool adop (AD Online Patching) utility.
• This edition is only present when patching is in progress 
• Changes do no affect the running Application
• Always the direct child of the Run Edition.
• Old Edition(s)
• There maybe zero or more Old Editions
• When the Patch Edition is promoted to production the previous Run Edition is now regarded as an Old Edition
• Only retained until a full cleanup operation is run 

File System
EBS 12.2 is installed with 3 file systems,All 3 file system forms Single E-Business Suite Instance and connect to a single database.

• FS-1 (Production file system),Used by the current users of the system
• FS-2 (Copy of Production file system), Where Actual Patching is done
• FS-NE (Non Editioned file system) ,Stores data that is stored on the file system

• In Release 12.2, all patching operations are carried out while the applications are in use and users are online.
• Patching is performed using the new adop (AD Online Patching) utility.
• A short period of downtime is required, but this amounts to little more than a restart of the services: the time the applications are unavailable is measured in minutes rather than hours, and this can be specified to be at the most convenient time.

The two files systems are rotated between Run and Patch during every patch cycle

• Run Edition
• The edition currently in use by the running application ,Used by Online Users
• Never changed by a Patch

• Patch Edition
• The edition currently in use by the patching tool adop (AD Online Patching) utility.
• This edition is only present when patching is in progress 
• Changes do no affect the running Application 
• Currently being patched
  or
  Waiting for the next patch cycle

  The Online Patching cycle consists of the following phases:

1. Prepare a virtual copy (patch edition) of the running application (run edition).
2. Apply patches to the patch edition of the application.
3. Finalize the system in readiness for the cutover phase.
4. Cutover to the patch edition and make it the new run edition.
5. Cleanup obsolete definitions or data to recover space.

This introduces the concept of a patching cycle that consists of several phases, in contrast to the model used in previous releases. These phases are denoted prepare, apply, finalize, cutover, and cleanup.


To support Online Patching Cycle phases, ADOP replaces ADPATCH utility to apply Application patches. In below diagram you can see how a patch is applied.

 

Prepare

• Patch Edition & Run Edition of the file systems are synchronized
• All files on the Patch Edition are an exact copy of the files on the Run Edition
• Patch Edition is created in the database
• All code objects in the Patch Edition begin as pointers to code objects in the Run Edition
• Storage objects such as tables are not copied

Apply

• Patches are applied to the copy (Patch Edition)
• Users are connected to the Application and can perform their work unaffected by the patch
• The running application is unaffected by these changes

Finalize

• Patches are applied to the copy (Patch Edition)
• Users are connected to the Application and can perform their work unaffected by the patch
• The running application is unaffected by these changes

Cutover

• During cutover a brief downtime is taken
• Middle-tier processes stopped
• File system roles swapped, where in Patched (FS-2) promoted to Run and FS-1 available for next patching cycle
• In Database Patch Edition promoted to Run Edition
• Middle-tier processes restarted

Cleanup

• Cleanup occurs after users have been brought back online to the newly patched Application
• In Database Code objects patched in the latest patching cycle are deleted from Old Editions.
• In File System it does not perform any task, except marking Pre-Patch File System ready for the next Patching Cycle. 

Apart from the above Five phases we have hidden phase, Abort some thing slimier to adworker hidden option ,The Online Patching Cycle can be aborted at any time prior to Cutover.