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.