WLM is code that runs on MVS mainframes. It can be queried
to ask about the load on the MVS machine. When MVS Workload Management
has been configured on your OS/390 system, Dispatcher can accept capacity
information from WLM and use it in the load balancing process.
Using the WLM advisor, Dispatcher will periodically open connections
through the WLM port on each server in the Dispatcher host table and
accept the capacity integers returned. Because these integers represent
the amount of capacity that is still available and Dispatcher expects
values representing the loads on each machine, the capacity integers
are inverted by the advisor and normalized into load values (that
is, a large capacity integer but a small load value both represent
a healthier server). The resulting loads are placed into the System
column of the manager report.
There are several important differences between the WLM advisor
and other Dispatcher advisors:
- Other advisors open connections to the servers using the same
port on which flows normal client traffic. The WLM advisor opens connections
to the servers using a port different from normal traffic. The WLM
agent on each server machine must be configured to listen on the same
port on which the Dispatcher WLM Advisor is started. The default WLM
port is 10007.
- Other advisors only assess those servers defined in the Dispatcher
cluster@port@server configuration for which the server's port
matches the advisor's port. The WLM advisor advises upon every
server in the Dispatcher configuration (regardless of the cluster@port).
Therefore you must not define any non-WLM servers when using the WLM
advisor.
- Other advisors place their load information into the manager report
under its “Port” column. The WLM advisor places its load information
into the manager report under its system column.
- It is possible to use both protocol-specific advisors along with
the WLM advisor. The protocol-specific advisors will poll the servers
on their normal traffic ports, and the WLM advisor will poll the system
load using the WLM port.
Metric Server Restriction: Like the Metric
Server agent, the WLM agent reports on server systems as a whole,
rather than on individual protocol-specific server daemons. Metric
Server and WLM place their results into the system column of the manager
report. As a consequence, running both the WLM advisor and Metric
Server at the same time is not supported.