Understanding DSN1CHKR Utility

Hello Everybody!!

Sometimes it is worth to verify the intigrity of DB2 directory and Catalog table spaces. DSN1CHKR utility is designed for this.
This utility checks the specified tablespace for

1) Broken Links
2) Broken Hash Chanins
3) Orphan records

This is a service aid and a diagonistic tool which executes outside the control of DB2.

Restriction:
You should not DSN1CHKR in a tablspace while it is active under DB2. Tablespace should be in STOPPED status before running this utility.

Privilege Required:
RACF auth required on the specified tablespace. No other privileges required to run this utility

Recommendation:
Copy the stopped tablespace into a similar VSAM dataset with DB2 naming convention and then run the utility on the copy.

Never run this utility on following tablespaces:

DSNDB06.SYSCOPY
DSNDB06.SYSDDF
DSNDB06.SYSGPAUT
DSNDB06.SYSPKAGE
DSNDB06.SYSSTATS
DSNDB06.SYSSTR
DSNDB06.SYSUSER
DSNDB01.SCT02
DSNDB01.SPT01
DSNDB01.SYSLGRNX
DSNDB01.SYSUTILX

Sample Job Step:

//**********************************************************************000
//**************** CHECKS CATALOG LINK & HASH CHAINS *****************000
//**********************************************************************000
//DH000701 EXEC PGM=DSN1CHKR,PARM='FORMAT' 000
//STEPLIB DD DSN=SYS1.DSN1.SDSNLOAD,DISP=SHR 000
//SYSPRINT DD SYSOUT=(2,,CRTL) 000
//SYSUT1 DD DSN=DSN1.DSNDBC.DSNDB01.DBD01.I0001.A001,DISP=SHR 000
//**********************************************************************000
//**************** CHECKS CATALOG LINK & HASH CHAINS *****************001
//**********************************************************************001
//DH000702 EXEC PGM=DSN1CHKR,PARM='FORMAT' 001
//STEPLIB DD DSN=SYS1.DSN1.SDSNLOAD,DISP=SHR 001
//SYSPRINT DD SYSOUT=(2,,CRTL) 001
//SYSUT1 DD DSN=DSN1.DSNDBC.DSNDB06.SYSDBASE.I0001.A001,DISP=SHR 001
//**********************************************************************001
//**************** CHECKS CATALOG LINK & HASH CHAINS *****************001
//**********************************************************************001
//DH000703 EXEC PGM=DSN1CHKR,PARM='FORMAT' 001
//STEPLIB DD DSN=SYS1.DSN1.SDSNLOAD,DISP=SHR 002
//SYSPRINT DD SYSOUT=(2,,CRTL) 002
//SYSUT1 DD DSN=DSN1.DSNDBC.DSNDB06.SYSDBAUT.I0001.A001,DISP=SHR 002
//**********************************************************************002
//**************** CHECKS CATALOG LINK & HASH CHAINS *****************002
//**********************************************************************002
//DH000704 EXEC PGM=DSN1CHKR,PARM='FORMAT' 002
//STEPLIB DD DSN=SYS1.DSN1.SDSNLOAD,DISP=SHR 002
//SYSPRINT DD SYSOUT=(2,,CRTL) 002
//SYSUT1 DD DSN=DSN1.DSNDBC.DSNDB06.SYSGROUP.I0001.A001,DISP=SHR 002
//**********************************************************************003
//**************** CHECKS CATALOG LINK & HASH CHAINS *****************003
//**********************************************************************003
//DH000705 EXEC PGM=DSN1CHKR,PARM='FORMAT' 003
//STEPLIB DD DSN=SYS1.DSN1.SDSNLOAD,DISP=SHR 003
//SYSPRINT DD SYSOUT=(2,,CRTL) 003
//SYSUT1 DD DSN=DSN1.DSNDBC.DSNDB06.SYSPLAN.I0001.A001,DISP=SHR 003
//**********************************************************************003
//**************** CHECKS CATALOG LINK & HASH CHAINS *****************003
//**********************************************************************003
//DH000706 EXEC PGM=DSN1CHKR,PARM='FORMAT' 004
//STEPLIB DD DSN=SYS1.DSN1.SDSNLOAD,DISP=SHR 004
//SYSPRINT DD SYSOUT=(2,,CRTL) 004
//SYSUT1 DD DSN=DSN1.DSNDBC.DSNDB06.SYSVIEWS.I0001.A001,DISP=SHR 004
//*

This is what IBM specified for the Sample JCL:
//YOUR JOBCARD
//*
//JOBCAT DD DSNAME=DSNCAT1.USER.CATALOG,DISP=SHR
//STEP1 EXEC PGM=IDCAMS
//********************************************************************
//* ALLOCATE A TEMPORARY DATA SET FOR SYSDBASE *
//********************************************************************
//SYSPRINT DD SYSOUT=A
//SYSUDUMP DD SYSOUT=A
//SYSIN DD *
DELETE -
(TESTCAT.DSNDBC.TEMPDB.TMPDBASE.I0001.A001) -
CATALOG(DSNCAT)DEFINE CLUSTER -
( NAME(TESTCAT.DSNDBC.TEMPDB.TMPDBASE.I0001.A001) -
NONINDEXED -
REUSE -
CONTROLINTERVALSIZE(4096) -
VOLUMES(XTRA02) -
RECORDS(783 783) -
RECORDSIZE(4089 4089) -
SHAREOPTIONS(3 3) ) -
DATA -
( NAME(TESTCAT.DSNDBD.TEMPDB.TMPDBASE.I0001.A001)) -
CATALOG(DSNCAT)
/*
//STEP2 EXEC PGM=IKJEFT01,DYNAMNBR=20
//********************************************************************
//* STOP DSNDB06.SYSDBASE *
//********************************************************************
//STEPLIB DD DSN=prefix.SDSNLOAD,DISP=SHR
//SYSTSPRT DD SYSOUT=A
//SYSPRINT DD SYSOUT=A
//SYSTSIN DD *
DSN SYSTEM(V61A)
-STOP DB(DSNDB06) SPACENAM(SYSDBASE)END
/*
//STEP3 EXEC PGM=DSN1COPY,PARM=(CHECK)
//********************************************************************
//* CHECKSYSDBASE AND RUN DSN1COPY *
//********************************************************************
//STEPLIB DD DSN=prefix.SDSNLOAD,DISP=SHR
//SYSPRINT DD SYSOUT=A
//SYSUT1 DD DSN=DSNCAT.DSNDBC.DSNDB06.SYSDBASE.I0001.A001,DISP=SHR
//SYSUT2 DD DSN=TESTCAT.DSNDBC.TEMPDB.TMPDBASE.I0001.A001,DISP=SHR
/*
Example 2:
To Run DSN1CHKR on an actual table space. STEP1 stopsdatabase DSNDB06 with the STOP DATABASE command. STEP2 runsDSN1CHKR on the target table space; its output is identical to the output inExample 1. STEP3 restarts the database with the START DATABASE command.
//STEP4 EXEC PGM=IKJEFT01,DYNAMNBR=20
//********************************************************************
//* START DSNDB06.SYSDBASE *
//********************************************************************
//STEPLIB DD DSN=prefix.SDSNLOAD,DISP=SHR
//SYSTSPRT DD SYSOUT=A//SYSPRINT DD SYSOUT=A
//SYSTSIN DD *DSN SYSTEM(V61A)
-START DB(DSNDB06) SPACENAM(SYSDBASE)END
/*
//STEP5 EXEC PGM=DSN1CHKR,PARM='MAP=RID(00000201,06,00000B01,06)',
// COND=(4,LT)
//********************************************************************
//* CHECKLINK S OF SYSDBASE *
//********************************************************************
//STEPLIB DD DSN=prefix.SDSNLOAD,DISP=SHR
//SYSPRINT DD SYSOUT=A
//SYSUT1 DD DSN=TESTCAT.DSNDBC.TEMPDB.TMPDBASE.I0001.A001,DISP=SHR
/*

Thanks for reading this blog

Cheers
Prakash C. Singh
IBM Certified DB2 DBA