This chapter provides an overview of the upgrade process and upgrade environments, and describes the utility used to perform the upgrade. Also review the topics that are relevant to the z/OS upgrade in the chapters in Siebel Database Upgrade Guide that provide an overview of the upgrade process and that describe how the Siebel database upgrade works. This chapter includes the following topics:

• About Supported Siebel Upgrade Paths
• About Using Oracle's Application Expert Services
• About Unicode Support
• About Siebel Upgrade Environments
• About the z/OS Upgrade
• About the Staging Database
• About Siebel Additive Schema Upgrade Changes
• About the Siebel Database Upgrade Process
• About the Siebel Database Configuration Utilities and Database Configuration Wizard
• About the Siebel Upgrade Wizard and Driver Files
• Job Flow of a Production Database Upgrade
• About the Override File