Determining Where to Route Work

The IWMSRSRS macro returns a list of eligible servers, and for each server, an associated weight. From this list, a client can determine where to route work. See z/OS® MVS™ Data Areas, Vol 3 for the mapping.

The weights provided allow changes in system conditions and server availability to be factored into the distribution of work. The weights represent the relative number of requests each server should receive. Various capacity considerations are used to calculate the weights.

A client can route the work to the servers as ordered in the list, and can route the number of requests as suggested for each server. A caller should be aware of other clients in the sysplex issuing the IWMSRSRS macro, and route work properly.

For example, if the list consists of the following:

  Server               Weight
  ------               ------
  NETID1.LUNAMEA          3
  NETID2.LUNAMEB          8
  NETID3.LUNAMEC          2

then the client should route the first 3 requests to NETID1.LUNAMEA, the next 8 to NETID2.LUNAMEB, and so on. When the client has gone through the list, the client can either invoke IWMSRSRS again for a refreshed list, or rotate through the list again.

Acceptable weights are from 1 to 64. If a server is busy, and not available to receive any work requests, it will not appear in the list. If work is routed to the server and it is not able to process the request, the request is not processed.

Clients should issue this macro on a regular basis, so that the list is refreshed every one to three minutes. This way, a client can stay current with changing system loads and server viability.

For complete information about the IWMSRSRS macro, see IWMSRSRS macro — Sysplex Routing Information.