Troubleshooting
Problem
The network LPAR was not responding to operator commands. Syslog contains many IST663I message groups.
Cause
A dump shows the NET task TCB enqueued on the SYSIEFSD Q10 resource. The console tasks IEAVG616 (handles commands and DOMs from other systems in the sysplex) and IEAVMQWR (handles the input from consoles on this system) are both queued behind the NET task.
The system log shows thousands of messages similar to the following:
IST663I CDINIT REQUEST FROM MYCDRM FAILED, SENSE=xxxxxxxx IST664I REAL OLU=NETA.T9060ABC REAL DLU=NETA.CICS2 IST889I SID = E23B561E2F477A18 IST264I REQUIRED LOGMODE NAME LU62IS UNDEFINED IST314I END
The IPCS SUMMARY FORMAT shows the TCB for ISTINM01 has the PRB PSW showing the following:
- ISTINCF9 has issued QEDIT (svc x'22') to have Commtask clean up the control blocks for a MODIFY command that was processed.
- Under the PRB is an SVRB for the qedit that's currently in IEE0303D.
- Under that SVRB is the VTAM IRB under which VTAM is processing all the requests that are resulting in the IST663I message groups. All of this synchronous processing will be done to completion under the IRB. All of the queued synchronous session requests will be processed under this IRB before the PRB is resumed and the QEDIT completes.
Resolving The Problem
Avoid the processing overhead of the error session flows. Most of the processing time for the error flows is going to be in the error message (IST663I) processing. Here are three ways to address this:
- Fix the reason for the session failure messages so that the high amount of error processing is not required.
- Use the VTAM flooding table to suppress the IST663I group based on, for example, sense code. The SNA Resource Definition Reference discusses this table and how to update it.
- Use the VTAM start options related to messages to reduce the number of messages. These start options are listed in a "Messages Start Options" table in the SNA Resource Definition Reference, and they include ASIRFMSG, DSIRFMSG, ESIRFMSG, FSIRFMSG, LSIRFMSG, RSIRFMSG, and SIRFMSG.
Note that the current values of these options can be displayed with the following command:
D NET,VTAMOPTS,FUNCTION=MESSAGES.
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Document Information
Modified date:
15 June 2018
UID
swg21179702