DB - Database service aids

You can use service aids, such as the IMS test program (DFSDDLT0), as well as various diagnostic techniques, to analyze problems with IMS databases.

Job control block trace
The job control block (JCB) trace is one of most useful diagnosis tools for any application problem that might occur. The trace is an easy way to determine the last five calls that were issued, and what their return codes were.
DL/I test program - DFSDDLT0
The DL/I test program is an IMS application that issues calls to DL/I based on control statement information. For diagnostic purposes, this allows you a means of separating the application logic from DL/I logic to resolve problems.
COMPARE statement SNAPs
When a DL/I call does not produce the results you expect, you can use the COMPARE statement to compare the actual results of a call with the expected results. The normal output of this statement usually provides enough information to determine what is causing the problem.
SNAPs on exceptional conditions
IMS produces SNAPs of DL/I control blocks on the IMS log (or the CICS® system log).
DL/I call image capture
DL/I call image capture (module DFSDLTR0) enables you to trace and record all DL/I calls issued by an application program. The trace output is in a format acceptable as input to the DL/I test program DFSDDLT0.
DL/I analysis
Debugging suggestions for a batch environment, including DL/I and DBB regions are described.
Locating database-related traces
Locating Retrieve trace, JCBTRACE, DL/I trace and LOG data set are shown.
DL/I trace
The DL/I trace table is a combined trace consisting of entries from DL/I calls, the DL/I buffer handler, DL/I OPEN/CLOSE, HD space management, lock activity (using PI or IRLM), OSAM, DFP interface, HALDB OLR trace, and ABENDU0427.
Retrieve trace
When an application program executes and a problem occurs (such as damaged data or unexpected results), you can use the Retrieve trace records to see how IMS responded to various calls in the application.
Online Recovery Manager trace
The Online Recovery Manager trace (ORTT) records the control flow that is related to /RECOVER command processing.
Program isolation-related problem analysis
When invalid segment data is retrieved, or an unexpected user abend occurs during concurrent updates to a single database by more than one processing region under the protection of program isolation, improper enqueue or dequeue logic has been followed in IMS. Tools are available to properly document this occurrence. Correct and adequate documentation might depend on the ability to reproduce the error condition and on the availability of IBM® Software Support.
Log analysis (database related)
The IMS log is one of the most useful of all IMS service aids. Understanding log records and what information they contain can be very beneficial.
Sequential buffering service aids
When you receive a message or abend that indicates a problem with sequential buffering (SB), several diagnostic tools are available. Some of these tools are useful for diagnosing other IMS database-related problems.
GSAM control block dump - DFSZD510
When a GSAM error occurs or when a DUMP or SNAP call is issued to a GSAM PCB, a formatted dump of the GSAM control blocks is written to the file that is defined as DDNAME IMSERR or SYSPRINT. You can use this GSAM control block dump (named DFSZD510) to diagnose GSAM problems.

Parent topic: Diagnosis