A Sysplex is a collection of System z™ servers that cooperate, using hardware and software, to process work. The Sysplex coordinates the cooperation by increasing the number of processors working together, which increases the amount of work that can be processed. In addition to an increase in processing capability, a Sysplex can provide flexibility in mixing levels of hardware and software, and in dynamically adding systems.
Sysplex permits DB2 Connect™ to seamlessly balance connections across different members of a data sharing group. Sysplex also provides DB2 Connect the means to try alternate members should a failure occur with one member. The rerouting capability for Sysplex is a DB2 Connect feature. DB2 Connect support for Sysplex is enabled by default and so is the rerouting capability for Sysplex. Sysplex support to a host database can be turned off by removing the SYSPLEX parameter from its DCS directory entry, but the DCS entry itself should not be removed, even if it has no other parameter specified.
With the automatic client reroute capability for Sysplex, the default behavior is for a Sysplex enabled connection to retry on the connect when there is a communication failure. Special register values up until the last successful transaction not holding resources are replayed when DB2 Connect is connected to a DB2® for z/OS® server.
You can configure the exact automatic client reroute retry behavior, including disablement, by using the DB2_MAX_CLIENT_CONNRETRIES and DB2_CONNRETRIES_INTERVAL registry variables. The connection timeout registry variable is DB2TCP_CLIENT_CONTIMEOUT.
Related concepts
Configuring automatic client reroute and High Availability Disaster Recovery (HADR)
Related reference
Configuring automatic client reroute retry behavior using registry variables