IBM Support

Collecting PEX Trace Data to Show What Job(s) Are Consuming Disk Space

Troubleshooting


Problem

This document provides information about how to identify what job or jobs are consuming disk space.

Resolving The Problem

Caution: A working knowledge of QUERY/400 and QSECOFR authority is required.


Note: Ensure that current list of PEX PTFs have been loaded prior to tracing from the iDoctor website.

To determine what job(s) are consuming disk space, do the following:
1 On the IBM operating system command line, type the following:

ADDPEXDFN DFN(DISKIO) TYPE(*TRACE) JOB(*ALL) MAXSTG(4000000) INTERVAL(200) TRCTYPE(*DSKSTG)

Press the Enter key.

Note: This PEX definition used will collect PEX events CRTSEG, DLTSEG, EXDSEG, TRUNCSEG, and FNDSEGSIZ. These events will be collected as *FORMAT1, which does not collect callstacks.

Note: If the data is being collected at the request from service, the following definition should be used:
ADDPEXDFN DFN(ASM) TYPE(*TRACE) JOB((*ALL *ALL)) TASK(*ALL) MAXSTG(4000000) TRCTYPE(*SLTEVT) SLTEVT(*YES) MCHINST(*NONE) STGEVT((*CRTSEG *NONE *FORMAT2) (*DLTSEG *NONE *FORMAT2) (*EXDSEG *NONE *FORMAT2) (*TRUNCSEG *NONE *FORMAT2) (*FNDSEGSIZ))

Press the Enter key.
2 On the IBM operating system command line, type the following:

STRPEX SSNID(RUN1) DFN(DISKIO)

Press the Enter key. Allow this to run until disk space increases by 3 to 5 percent.
3 On the IBM operating system command line, type the following:

ENDPEX DTALIB(qpexdata) RPLDTA(*YES)

Press the Enter key.
4 On the IBM operating system command line, type the following:

PRTPEXRPT MBR(RUN1) LIB(qpexdata) TYPE(*TRACE) OUTPUT(*OUTFILE) +
OUTFILE(qpexdata/DISKIO)

Press the Enter key.
5 IBM Query (WRKQRY) can now be used to query the file qpexdata/DISKIO.

The following query is an example:

Selected files
ID File Library Member Record Format
T01 DISKIO QPEXDATA RUN1 QVPETRC

Result fields
Name Expression Column Heading Len Dec
TYPE substr(QTREID, 1, 3) Operation Type
Select record tests
AND/OR Field Test Value (Field, Numbers, or 'Characters')
QTREID EQ 'CRT *'
OR QTREID EQ 'EXT *'
OR QTREID EQ 'DST *'
OR QTREID EQ 'TRN *'
AND QTRBLN GT 0

Note: All values are reported as a positive value; however, type DST and TRN are destroy and truncate. Therefore, these must be treated as negative values. To get a true indication of the space increase, manually calculate the sum (CRT+EXT) - sum(DST+TRN) for each job.

Ordering of selected fields
Name Sort Priority Ascending/Descending Break Level Field Text
QTRTNM
QTROBN 10 A 1 Job/Task name
QTROBL Object Library
QTROTP Object Type (hex)
QTREVT Trace event type
QTREVS Trace event subtype
TYPE 20 A 1 Operation Type
QTRBLN Operation byte length

Report column formatting and summary functions

Summary functions: 1-Total, 2-Average, 3-Minimum, 4-Maximum, 5-Count Overrides
 
Field Name Summary Functions Column Spacing Column Headings Len Pos Dec
Cap
Null
Len
Dec Pos Editing
QTRTNM 0 Job/Task Name 30
QTROBL 2 Object Library 10
QTROBN 2 Object Name 20
QTROPT 2 Object Type 4
QTREVT 2 Type 2 0
QTREVS 2 Sub-Type 2 0
QTREID 2 Event ID 6
QTRBLN 1 2 Operation 20 0


Report breaks
Break Level New Page Suppress Summaries Break Text
0 No Yes
1 No Yes
2 No No OPERATION

This query creates a spooled file that lists all of the jobs that created, expanded, deleted/destroyed, and truncated objects. To identify the job or jobs that are the root cause of the increase of disk usage, the create and expanded entries from the destroyed and truncated entries must be manually subtracted.

Another option available, in determining disk usage, is to purchase an IBM tool called iDoctor Pex Analyzer. iDoctor Pex Analyzer is capable of analyzing many different types of performance problems including determining disk usage. 

Note: iDoctor analysis for space growth may require a statement of work with our Expert Labs consultants. 

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Historical Number

24811858

Document Information

Modified date:
14 January 2025

UID

nas8N1017212