Troubleshooting
Problem
You are experiencing a shared channels problem in IBM MQ for z/OS. You would like to know what documentation you must collect (MustGather) so that the IBM MQ Support team can diagnose your problem. If you gather this documentation before contacting support it will expedite the troubleshooting process, and save you time.
Resolving The Problem
Gather this MustGather data before contacting IBM Support:
Collecting general data for all problems
Collecting troubleshooting data for this problem
Troubleshooting hints and tips
Exchanging data with IBM Support
Go back to: IBM MQ (MustGather) Read First
Collecting general data for all problems
A complete description of the problem, including the following:
- IBM MQ version, release, and maintenance level
- Operating system version, release, and maintenance level
- Related products version, and release levels if applicable
Collecting troubleshooting data for this problem
Required (MustGather) data:
- z/OS Job logs.
Because a shared channel can be active on any qmgr in the QSG, the joblogs of all the queue managers and CHINs may be needed. - Dumps generated at point of failure.
Optional (MustGather) data:
- Logrec (JCL to get software LOGREC report).
- Dumps of the MSTR and CHIN requested at the point of failure with MSTR and CHIN trace active.
- Output from MQ commands, where cpf is the command prefix for the queue manager:
- /cpf DISPLAY CHINIT
This shows: - Which listeners are started, and information about them.
- How many dispatchers, adapter subtasks, and SSL subtasks are started, and how many were requested.
- The TCP system name.
- How many channel connections are current, and whether they are active, stopped, or retrying.
- The maximum number of current connections.
- /cpf DISPLAY CHSTATUS(xx) CURRENT to get current status.
- /cpf DISPLAY CHSTATUS(xx) SAVED for saved status.
- /cpf DISPLAY CHANNEL(xx) to obtain channel definition.
- CSQUTIL COPY of SYSTEM.QSG.CHANNEL.SYNCQ. This is where shared channels write their sync queue information. See the Example JCL in the IBM MQ for z/OS System Administration Guide.
- A dump of the ADMIN structure: Shared channels are serialized applications. Serialized information is stored in the QSG Admin structure.
/dump comm=(title)
/r xx,strlist=(strname=QSGnameStructurename,(listnum=all,
An example of QSGnameStructurename is CSQ1CSQ_ADMIN where CSQ1 is the queue manager subsystem name.
- For outbound channels, a dump of the structure where the shared XMITQ is defined
- SPUFI output of the shared channel status DB2 tables:
SELECT * FROM CSQ.ADMIN_B_SCST ;
SELECT * FROM CSQ.ADMIN_B_SSKT ; - z/OS TCP/IP PKTTRACE.
Troubleshooting hints and tips
- Search the IBM MQ support site for known problems using symptoms like the message number and error codes.
- Gather the documentation and work with the IBM MQ support team to resolve your problem.
- See technotes and APARs relating to shared channels.
- See technotes and APARs related to DVIPA (Dynamic Virtual IP Address) for shared inbound channels.
- Technical Exchange - Troubleshooting Communication in IBM MQ and WebSphere MQ Distributed Queuing Overview and Common Problems on z/OS.
- Performance issues:
- Do DISPLAY CHSTATUS on both ends of the channel and check STATUS, SUBSTATE and INDOUBT.
- Use a monitor or RMF data to confirm that the CHIN or TCP/IP task is not suffering dispatching delays due to WLM settings or CPU constraint.
- Be aware that TCP/IP sockets created by the MQ CHINIT take the default send and receive buffer sizes from the TCP/IP profile. If you are using z/OS 1.11 or 1.12, TCP/IP APAR PM16788 should be applied.
- Review a packet or other network trace to see if TCP retransmissions or window sizing are causing delays.
Learn more about this component
- IBM MQ for z/OS concepts: section Distributed queuing and queue-sharing groups.
- Setting up communication for IBM MQ for z/OS using queue-sharing groups.
- Library and Information center.
Exchanging data with IBM Support
- See Exchanging information with IBM Technical Support for FTP and email instructions using the IBM Enhanced Customer Data Repository (ECuRep).
- Go to the Service Request page to open or update a problem.
Note: Always update your Service Request (problem record) to indicate that data has been sent.
If you need to speak to an IBM technical support representative call your country representative. If you need to speak to an IBM technical support representative in the US call 1-800-IBM-SERV.
Product Synonym
WMQ MQ
Was this topic helpful?
Document Information
Modified date:
21 June 2018
UID
swg21243378