XDAB Command: Trace VSAM I/O Events

Commands › XDAB Command: Trace VSAM I/O Events

XDAB Command: Trace VSAM I/O Events

To trace VSAM I/O events and send the trace data to a sysout data set, use the XDAB command.

Note: XDAB is a diagnostic tool. Do not use under normal operating conditions.

Type: OPER command

Authority: To issue the XDAB command, you require OPER authority.

This command has the following format:

XDAB SET|T TRACE|TR
     [SYSOUT(class)]|[LOGTRACE]
     [ASYNC|ALL]
     [LOCK|NOLOCK]
     [RESERVE|NORESERVE]

XDAB {START|S}
     {STOP|P}
     {RESTART|RES|RS|SPIN|SP}
     {DISPLAY|D}
     TRACE|TR

XDAB HELP|H|?

SYSOUT(class): Send VSAM I/O trace data to a sysout data set with DDNAME DABTRACE and to the class that class specifies.
LOGTRACE: Send VSAM I/O trace data to a sysout data set with DDNAME LOGTRACE. The trace data is consolidated with certain other trace data.
ASYNC: Include only asynchronous VSAM I/Os in the trace data.
ALL: Include asynchronous and synchronous VSAM I/Os in the trace data.
LOCK: Include internal VSAM data set locking and unlocking events in the trace data.
NOLOCK: Exclude internal VSAM data set locking and unlocking events from the trace data.
RESERVE: Include VSAM data set cross-system serialization events in the trace data.
NORESERVE: Exclude VSAM data set cross-system serialization events from the trace data.
START|S: Start the VSAM I/O tracing.
STOP|P: Stop the VSAM I/O tracing.
RESTART|RES|RS|SPIN|SP: Stop and restart the VSAM I/O tracing.
DISPLAY|D: Display the current XDAB status.
HELP|H|?: Display the XDAB command operands.

Set Up the Trace

Do this task before you start the trace. Set up the trace by issuing XDAB with at least the SYSOUT or LOGTRACE operands. If you issue XDAB with the LOGTRACE operand, set up the trace data consolidation.

Start Trace Data Consolidation

When you specify the LOGTRACE operand, data for the XDAB trace is not generated. Additionally, data for the XDAB trace is not consolidated with data from other traces until you start the XDAB trace and start the trace consolidation.

Displaying Trace Settings

Issue XDAB SET TRACE alone to display the current settings for the XDAB tracing.

Asynchronous I/Os

Some VSAM data set I/Os, such as the JOBINDEX file I/Os, are asynchronous for performance reasons. z/OS Agent main task is not suspended when a wait is required for an asynchronous I/O completion.

Related Information

See the XDAB initialization parameter in the Initialization and Configuration Guide.
See the LOGTRACE Command.

Example: Display the Current Settings for XDAB Tracing

These two examples show how to display XDAB trace settings.

XDAB DISPLAY TRACE
XDAB D TR

Example: Set the Sysout Class for XDAB Trace Data

This example shows how to specify that trace data goes to DDNAME DABTRACE with the sysout class set to A.

XDAB SET TRACE SYSOUT(A)

Example: Consolidate XDAB Trace Data with Other Trace Data

This example shows how to specify that trace data goes to the DDNAME LOGTRACE, and the trace data is consolidated with certain other trace data.

XDAB SET TRACE LOGTRACE

Example: Filter XDAB Trace Data

This example shows how to limit the trace data to asynchronous VSAM I/Os and include VSAM data set cross-system serialization events in the trace.

XDAB SET TRACE ASYNC RESERVE

Example: Control the XDAB Trace

This example shows how to start the XDAB trace.

XDAB START TRACE

This example shows how to restart the XDAB trace.

XDAB SP TRACE

Example: Get Help

This example shows how to display the operands for the XDAB command.

XDAB ?