Connection monitoring and CPU utilization charts for the DB2 Connect performance tests explained

This section contains information on how we monitored our active connections as well as a sample CPU utilization chart.

Monitor active connections

The following information describes how we monitored the connections.

WebSphere® - In the administrative console, we clicked Monitoring and Tuning > Performance Viewer > Current activity. We then checked the following fields:

Connection pools - The connection pool summary lists all data source connections that are defined in the application server and shows their usage over time.
Thread Pools - The thread pool summary shows the usage of all thread pools in the application server over time.

DB2 Connect - On the DB2 Connect server guest we ran a script that counted the number of database agent processes running every 30 seconds during the test.

z/OS® - The z/OS for DB2® command to display the active connection is -dis ddf detail. An example of the output produced by this command is shown below.

Note: Bold is added for emphasis only.

 DSNL080I  -DB91 DSNLTDDF DISPLAY DDF REPORT FOLLOWS:                  
 DSNL081I STATUS=STARTD                                                
 DSNL082I LOCATION           LUNAME            GENERICLU               
 DSNL083I DB91ZOS            USIBMT6.DB91ZOS   -NONE                   
 DSNL084I TCPPORT=446   SECPORT=0     RESPORT=447   IPNAME=-NONE       
 DSNL085I IPADDR=::9.12.22.95                                          
 DSNL086I SQL    DOMAIN=lndia3.pdl.pok.ibm.com                         
 DSNL086I RESYNC DOMAIN=lndia3.pdl.pok.ibm.com                         
 DSNL090I DT=I  CONDBAT=  10000 MDBAT= 1000                            
 DSNL092I ADBAT=  198 QUEDBAT=      0 INADBAT=      0 CONQUED=      0  
 DSNL093I DSCDBAT=     85 INACONN=    320                              
 
 DSNL099I DSNLTDDF DISPLAY DDF REPORT COMPLETE

The following fields are associated with DDF threads and connections:

condbat: Maximum number of inbound connections as determined by the "MAX REMOTE CONNECTED" value in the DSNTIPE installation panel. This value must be greater or equal to the total number of connections expected to be open at the same time, especially as the value of mdbat.
mdbat: Maximum number of database access threads as determined by the "MAX REMOTE ACTIVE" value in the DSNTIPE installation panel. This effectively determines the maximum number of active slots. That is, the maximum number of concurrent active database access threads that could potentially be executing SQL.
adbat: Current number of active database access threads. This value increases as new database access threads get created or become active. The value decreases as database access threads terminate or become inactive. When this value reaches or exceeds the mdbat value that is indicated in the DSNL090I message, new or inactive database access threads (DBATs), or new or inactive connections must be queued, which leads to an increasing response time. When this value exceeds the condbat value, new connection requests are rejected.

CPU utilization charts explained

In the charts in this report, the CPU utilization values are always normalized in a way that 100% means one CPU is fully utilized.

Figure 1 is an example of a CPU utilization chart for a z/OS LPAR and a z/VM® LPAR in relation to z/VM guest CPU utilization.

db2c14 — Figure 1. Sample CPU utilization chart

The CPU utilization charts show the utilization for each LPAR (z/VM or z/OS) by a line with triangle symbols. The details of how the z/VM guests use the CPUs is shown with stacked bars, which should sum up to the z/VM utilization without the CP related CPU part, so it is always a little lower than the z/VM LPAR utilization. If the CPU utilization from a guest in the legend is not visible, that means it is too low to display.