What are the recommended values for the parameters MESSAGEMAX and COMMANDMAX to prevent an emergency shutdown of OPS/MVS.
Possible error messages due to one of these parameter values being exceeded:
OPS3146S EMERGENCY PRODUCT SHUTDOWN STARTED - MAXIMUM COMMAND RATE EXCEEDED
OPS3146S EMERGENCY PRODUCT SHUTDOWN STARTED - MAXIMUM MESSAGE RATE EXCEEDED
How to prevent this situation.
Release : 13.5
Component : OPS/MVS
Many customers use the values below for these parameters:
As a general rule, check the value of the parameter COMMANDHIGH and MESSAGEHIGH on the OPSVIEW panel 4.1.1. If they are reaching their respective maximum values then consider to increasing these values.
NOTE: There are no repercussions to overhead, process blocks, etc by increasing these values. The main consideration is to set the value high enough so that an emergency shutdown is not invoked unnecessarily, but high enough so as to stop any run-away process.
* Besides COMMANDMAX and COMMANDRATE there are some other parameter that may help you tuning this scenario.
OPS/MVS keeps a counter of commands issued in the COMMANDCURRENT display-only parameter. When COMMANDCURRENT reaches the value of COMMANDMAX the emergency shutdown occurs.
* COMMANDRATE is value that is decremented from COMMANDCURRENT at each second. This mechanism makes COMMANDCURRENT kind of a buffer with size equal to the value of the parameter COMMANDMAX to allow OPS to issue commands at a higher rate during short periods of time. Only when the number of commands issued remains high for a longer period all the "buffer" becomes full because the rate at each the commands are removed from there (COMMANDRATE) is not enough to avoid that COMMANDCURRENT reaches COMMANDMAX.
* There is another parameter that can help determine the values of COMMANDMAX and COMMANDRATE that is COMMANDHIGH. If you monitor the value of COMMANDHIGH you will know how close your OPS region is/was from reaching COMMANDMAX since it was last started. If you see COMMANDHIGH approaching COMMANDMAX then you should first investigate if this was due to normal processing and then adjust the values of COMMANDMAX and COMMANDRATE accordingly.
* You can change COMMANDHIGH dynamically in the OPSVIEW panel 4.1.1 in case you want to reset its value to start a new period of monitoring.
We encourage review of these parameters in the Parameter Reference of the documentation.