The manager uses ratios to determine the importance of
status information coming from advisors and Load Balancer. You can
change the default ratios that the manager uses to weight this information.
About this task
The manager can use some or all of the following external
factors in its weighting decisions:
- Active connections: The number of active connections on each load
balanced server machine (as tracked by the executor), or
- CPU (in the case of the Site Selector component, based on input
from the Metric Server)
- New connections: The number of new connections on each load balanced
server machine (as tracked by the executor), or
- Memory (in the case of the Site Selector component, based on input
from the Metric Server)
- Port-specific: The input from advisors listening on the port.
- System metric: The input from the system monitoring tools, such
as Metric Server or WLM.
Along with the current weight for each server and some
other information required for its calculations, the manager gets
the first two values (active and new connections) from the executor.
These values are based on information that is generated and stored
internally in the executor.
You can change the relative proportion
of importance of the four values on a per cluster basis. Think of
the proportions as percentages; the sum of the relative proportions
must equal 100%. The default ratio is 50/50/0/0, which ignores the
advisor and system information. In your environment, you may need
to try different proportions to find the combination that gives the
best performance.
Note: - When adding an advisor (other than WLM), if the port proportion
is zero, then the manager increases this value to 1. Because the sum
of the relative proportions must total 100, the highest value is then
decreased by 1.
- When adding the WLM advisor, if the system metric proportion is
zero, then the manager increases this value to 1. Because the sum
of the relative proportions must total 100, the highest value is then
decreased by 1.
The number of active connections is dependent
upon the number of clients as well as the length of time necessary
to use the services that are being provided by the load balanced server
machines. If the client connections are quick (such as small Web pages
served using HTTP GET), then the number of active connections are
fairly low. If the client connections are slower (such as a database
query), then the number of active connections are higher.
You
should avoid setting active and new connections proportions values
too low. You will disable load balancing and smoothing unless you
have these first two values set to at least 20 each.