DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

The JCC connection concentrator feature is available only when DB2 on z/OS is the target
server. If you need concentration function for connections to DB2 UDB databases for
distributed platforms, you need DB2 Connect today. Also, JCC connection concentrator only
works with T4 direct connection to DB2 servers. Both JCC connection concentrator and JCC
sysplex workload balancing features are automatically disabled if JCC driver detects that it is
connected to a DB2 server via a DB2 Connect gateway. In this case the DB2 Connect
gateway will be responsible for handling connection concentration and workload balancing.
Connection concentrator was designed for environments where a large number of clients are
connecting to the host and there is the need to limit the number of connections resources on
the host side. There is some overhead with switching applications to transports connected to
the host at the transaction level, but much of this overhead is incurred on client machines
where CPU and memory are less expensive and less constrained.
The same IRWW workload was run with the DB2 Connect configuration shown in
Figure 7-15.
Windows
Workstation
IRWW
Workload
Driver
Figure 7-15 JCC T2 and DB2 Connect configuration
AIX zSeries
WebShpere
JCC T2
DB2
Connect
LPAR D7
DB8A
LPAR D8
DB8B
The graph shown in Figure 7-16 compares the performance degradations of JCC T4 and DB2
Connect before and after both are configured to concentrate transports or agents with the
same connection-to-transport/agent ratio. This approach gives us a fair comparison of their
respective connection concentration and load balancing efficiency. The performance impact
on DB2 for z/OS is measured in normalized DB2 transactions per second (internal
throughput).
Chapter 7. Networking and e-business 301