Mainframe Problem Diagnosis Part 2

 

dumps

This post is part of mainframe diagnosis series.  Today we will discuss about diagnostic dumps.  This post is part 2 of the series.  Check part 1 post here

Dumps provide very useful diagnostic data related to the problem.  The problem could be in operating system, subsystem (example DB2,CICS etc), hardware or application.  A problem may arise at any time for example

  • Abnormal processing my occur in either operating system or application.
  • A job may hung in the system
  • A job may loop
  • i/o errors

A dump gives a snapshot of the system at the time of error.

  • Abend dumps
    Abend dumps the virtual storage of program. There are 3 types of ABEND dumps

    • SYSABEND – This dump contains inclusive data about the abending program and all other relevant data needed to diagnose the problem. This dump is formatted.
    • SYSMDUMP – This dump contains summary dump for abending program and system. This dump is not formatted and hence you need a tool like IPCS to debug.
    • SYSUDUMP – This dump contains data only about the abending program. This is smallest dump of all 3.
  • SLIP dumps
    Set Service Level Indication Processing (SLIP) traps to capture the dumps you requested of problem program. SLIP can intercept program event recording or error event. SLIP trap is set to catch an error and when it triggers it perform actions you specify.
  • SNAP dumps
    This dump is useful when testing a program. SNAP dump provides virtual storage of the testing program when it is running.  SNAP dumps at various stages of program run will give complete picture of program processing. You can request to SNAP dumps as little as 1 byte of program field.  This dump is pre-formatted and hence cannot be used with IPCS.
  • Standalone dumps
    This dump is produced when a system fails or stand alone dump program fails. This dump gives necessary information on why system failed or stand alone dump program failed. This dump contains central storage and virtual storage. The term standalone means that dump is produced separately from normal processing of the system.
  • SVC dumps
    SVC dumps are very useful in diagnosing the problem.  Usually a system component requests an SVC dump if an expected error occurs and system can still continue processing. SVC dump can also be requested by authorized program to solve a problem.  SVC dumps can be analyzed using IPCS.
  • Transaction dumps
    Transaction dumps provides virtual storage of the failing address space. Usually an application program request this dump from recovery routine when an unexpected error occurs.

reference: MVS knowledge center

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