Data Sharing for DB2 for z/OS 
You can use DB2 Data Sharing and SAP Sysplex Failover Support as a high-availability solution to protect the database of your SAP system against failure.
Note
This section is a schematic description. For more information, see the SAP NetWeaver Installation Guide on <your operating system>: IBM DB2 for z/OS at:
http://service.sap.com/instguidesNW
You can fully integrate DB2 Data Sharing and SAP Sysplex Failover Support with your SAP system.
To increase availability and scalability, you can set up DB2 for z/OS as a parallel database, known as DB2 data sharing. With this setup, multiple DB2 subsystems share the same SAP database. Each subsystem is called a data sharing member, and the set of subsystems is referred to as a data sharing group. All members of the group use the same shared DB2 catalog and directory. This setup is shown in the following graphic:

DB2 Data Sharing
SAP Sysplex Failover Support is the implementation of DB reconnect for DB2 for z/OS. It uses DB2 Connect as the connectivity software. It allows each application server to recognize more than one database server. In most cases, the database server is the primary database server. One or more standby database servers are used if the application server can no longer work with the primary database server. This can be caused by failure in any of the following:
DB2 subsystem and Distributed Data Facility (DDF)
z/OS system
Entire zSeries hardware
Network
SAP Sysplex Failover Support is configured by a profile that provides a list of database connections for each application server or group of application servers.For more information, see SAP Note 402078.
SAP Sysplex failover support is supported by transaction DB2 in the SAP system, with which you can do the following:
Active DB connections shows you the DB2 database servers currently connected
DB connection list lets you switch between the DB2 database servers
The DB2 JDBC Driver provides native support for database failover that can be exploited with SAP Java applications. For more information about this approach, see SAP Note 1085521.
IBM documentation: Business Continuity for SAP on IBM System z (SC33–8206)