Technical data
Using DNS to Balance Work Load
6.3 Load Broker Concepts
Availability is calculated using the IJOBLIM system parameters and the SDA
global reference variable IJOBCNT in the following equation:
availablity = (20*(IJOBLIM-IJOBCNT))/IJOBLIM
• Workload
One consideration in the work load calculation is the system manager’s
estimate of the host’s relative CPU power specified by the system logical
TCPIP$METRIC_CPU_RATING.
To set a CPU power value, use the DCL command DEFINE to define the
system logical name TCPIP$METRIC_CPU_RATING with a value. The CPU
rating value can range from 1 (the lowest CPU power) to 100 (the highest
CPU power). If a value is specified, the value is used instead of the term
(min(235,IJOBLIM) in the following equation.
workload = (min(235,IJOBLIM)*100)/(100+load_average)
When you set the logical value to 0, or if you do not define TCPIP$METRIC_
CPU_RATING, the metric server uses the value of the system parameter
IJOBLIM to calculate work load.
load_average
is an average of the current CPU load taken every second. It is
calculated by using 97.9% of the previous CPU load and 2.1% of the current
CPU load value.
• Penalty
The metric server uses the FREEGOAL system parameter and the SDA
global reference variable FREECNT to calculate an available memory penalty.
penalty = 40*((FREEGOAL+2048-FREECNT)/(FREEGOAL+2048))
The value of
penalty
is subtracted from the rating only if the value is
positive. If the value of FREECNT is high enough, the value of
penalty
is not
applied.
6.4 Load Broker Startup and Shutdown
The load broker can be shut down and started independently. This is useful when
you change parameters or logical names that require the service to be restarted.
The following files are provided:
• SYS$STARTUP:TCPIP$LBROKER_STARTUP.COM allows you to start up
the load broker service.
• SYS$STARTUP:TCPIP$LBROKER_SHUTDOWN.COM allows you to shut
down the load broker service.
To preserve site-specific parameter settings and commands, create the following
files. These files are not overwritten when you reinstall TCP/IP Services:
• SYS$STARTUP:TCPIP$LBROKER_SYSTARTUP.COM can be used as a
repository for site-specific definitions and parameters to be invoked when the
load broker is started.
• SYS$STARTUP:TCPIP$LBROKER_SYSHUTDOWN.COM can be used as a
repository for site-specific definitions and parameters to be invoked when the
load broker is shut down.
Using DNS to Balance Work Load 6–5