Prepare Phase - R12.2 Online Patching Cycle

This phase prepares the environment for patching by creating a copy of the current run edition. The copy is called as PATCH edition.
The exact actions taken during the prepare phase are context dependent.
For example the First time run you run prepare phase on an instance will be different from the second run.
It take different route after you perform abort or cutover

Prepare Phase - Internal Steps

• Checks Environment
• Cleanup if Required
• Database readiness 
• File system readiness
• Report Generation
• Checks Concurrent Program ADZDPATCH
• Sync Patches to the PATCH edition APPL_TOP
• Final Validation

Prepare Phase - Database and File system readiness

• Checks the FILE_EDITION environment variable value is set to 'run‘
• Checks to see if enough space is available in the database
• Checks if the database user is edition-enabled
• Checks to see if the patch service has been created
• Checks to see if logon trigger exists and is enabled
• Checks to see if enough space is available in the file system
• Checks to see if database connectivity is fine

Prepare Phase – ADZDPATCH concurrent program

• Checks for the existence of the "Online Patching In Progress" (ADZDPATCH) concurrent program
• This program prevents certain predefined concurrent programs from being started.
• If the ADZDPATCH program exists, a message to this effect is displayed to the user. If it does not exist, it is started.
• ADZDPATCH is cancelled when the cutover phase is complete

Prepare Phase – Sync Patches to the PATCH edition APPL_TOP

• Checks for the Patches that were applied in the last patching cycle with a cutover
• Applies all the patches in sequence to the PATCH edition if any

Prepare Phase  - Scenario

You have been asked to apply a patch and you start with the first phase “PREPARE”. Customer has recently applied two patches during the last downtime window.

You have been asked to apply a patch and you start with the first phase “PREPARE”. Another engineer has already run the prepare phase and for some reasons the engineer did not proceed further.

You have been asked to apply a patch and you start with the first phase “PREPARE”. Your terminal got disconnected when prepare phase was running or there was an outage and server got rebooted.

You have been asked to apply a patch after a fresh installation of R12.2.X. So you are running PREPARE phase for the first time on the instance.