Database High Availability 
This section describes in detail how you can minimize downtime caused by the SAP system database with the following databases (listed in alphabetical order):
IBM DB2 for i (abbreviated to “DB2 for i”
IBM DB2 for Linux, UNIX, and Windows (abbreviated to “DB2 for Linux, UNIX, and Windows” or “DB2 for LUW”)
IBM DB2 for z/OS (abbreviated to “DB2 for z/OS”)
There are several database-related tasks and situations that can cause downtime of the database or prevent single transactions from proceeding.
Implementation Considerations
The information in this section is useful whether you are installing the database for the first time, or considering ways to improve the availability of an existing installation. For detailed technical guidance when implementing a specific product or feature, contact the appropriate source, such as your SAP consultant, your database supplier, the SAP Competence Center, and so on.
Integration
High availability for the database must be part of a system-wide strategy for improving the availability of your SAP system. Therefore, also consider other components of the system, such as the SAP system itself, the network, the hardware, and the operating system services, and so on.
Features
You can find information on the following topics for each database:
Space Management (including configuration and reorganization)
Backup or archive
Recovery
Upgrade
More Information
Database Administration Using the DBA Cockpit: IBM DB2 for Linux, UNIX, and Windows at:
http://service.sap.com/instguidesnw 
<Your SAP NetWeaver Release> Operations Database-Specific Guides 