A fix is available
APAR status
Closed as program error.
Error description
ABEND04E RC00C90101 LOC=DSNIDM.DSNKDPG ERQUAL500A occurred during index page deletion when index fast traverse block(FTB) is in use. Additional Symptoms: ABEND 04E 00C90101 DSNKINSN ERQUAL 5009 DSNKFEXT 5001 5002 DSNKFLOK DB2FTB/K
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: * * All Db2 12 for z/OS data sharing users * * with in-memory index optimization function * * enabled (Index Fast Traverse Block-FTB). * **************************************************************** * PROBLEM DESCRIPTION: * * In a Db2 12 data sharing system, when * * index fast traverse block(FTB) is in * * use, ABEND04E RC00C90101,LOC=DSNIDM. * * DSNKDPG ERQUAL500A occurred during * * index page deletion. * * ABEND04E RC00C90101,LOC=DSNIDM. * * DSNKINSN ERQUAL5009 occurred * * during index page split. * **************************************************************** * RECOMMENDATION: * * Apply corrective PTF when available * **************************************************************** In a Db2 12 data sharing system, when FTB is in use, the Db2 member running SQL INSERT or SQL DELETE needs to use FTB physical lock (P-lock) to send notify messages to other Db2 members to update their FTB information when an index page split or deletion happens. The following problems exist in the FTB P-lock area: 1> If the FTB P-lock status maintained on each Db2 member has inconsistent state, the notify message will not work properly and FTB information can become inconsistent with the index non leaf page information, thus causing ABEND04E RC00C90101,LOC=DSNIDM.DSNKINSN ERQUAL5009 or ABEND04E RC00C90101,LOC=DSNIDM.DSNKDPG ERQUAL500A during index page split or page deletion. SQL query can return incorrect output when the index is used for query access. 2> In a small timing window, the FTB P-lock request and FTB P-lock exit returning out of order can cause the saved FTB P-lock token to have a zero value. The zero P-lock token will cause the ABEND04E RC00C90101,LOC=DSNIDM. DSNKDPG ERQUAL500A or ABEND04E RC00C90101,LOC=DSNIDM. DSNKINSN ERQUAL5009 when it is used to send notify messages to other Db2 members during index page deletion or page split. 3> ABEND04E RC00C90101,LOC=DSNIDM.DSNKFLOK ERQUAL5002 or ABEND04E RC00C90101,LOC=DSNIDM.DSNKFEXT ERQUAL5001 or ABEND04E RC00C90101,LOC=DSNIDM.DSNKFEXT ERQUAL5002 can be issued when Index FTB P-lock request or FTB P-lock exit detects an error, Db2 doesn't setup the proper program recovery routine (PRR) before issuing these ABENDs, which causes the Db2 system crash. 4> The FTB Intent Share (IS) P-lock can be released when an index page set is converted to read only mode or become non group buffer pool (GBP) dependent. In a small timing window, if the FTB is created while the IS P-lock is released, the FTB can be created without holding the proper P-lock.
Problem conclusion
Db2 code has been updated in the FTB P-lock area to provide the following fixes: 1> After the FTB is created for an index, the Db2 member which creates the FTB will send the notify messages to other Db2 members to verify their FTB P-lock state. When an invalid FTB P-lock state is detected, ABEND04E RC00C90101 LOC=DSNIDM.DSNK1CNE ERQUAL5005 and ABEND04E RC00C90101 LOC=DSNIDM.DSNKFTBU ERQUAL5061 will be issued and the newly created FTB will be freed. This will prevent the data integrity issue caused by the inconsistent FTB P-lock. 2> When the FTB P-lock request and P-lock exit return out of order, the FTB P-lock token will be saved with a valid non zero value. 3> FTB P-lock request and P-lock exit are changed to setup the proper program recovery routine to avoid Db2 crash when an ABEND is issued. The non zero return code will be returned from the P-lock exit so the P-lock requester can detect the error and fail the P-lock request. IRLM APAR PH25240 also needs to be installed to provide this fix. 4> FTB IS P-lock will not be released when an index page set is converted to read only mode or become non GBP dependent.
Temporary fix
********* * HIPER * *********
Comments
APAR Information
APAR number
PH24667
Reported component name
DB2 OS/390 & Z/
Reported component ID
5740XYR00
Reported release
C10
Status
CLOSED PER
PE
NoPE
HIPER
YesHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2020-04-21
Closed date
2020-06-02
Last modified date
2020-07-06
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI69831
Modules/Macros
DSNKISPL DSNKULTH DSNKFQPL DSNKUNR2 DSNK1CNE DSNKDPG DSNKFEXT DSNB1CPL DSNKFTBU DSNKFLOK DSNKINSN DSNKMDEL
Fix information
Fixed component name
DB2 OS/390 & Z/
Fixed component ID
5740XYR00
Applicable component levels
RC10 PSY UI69831
UP20/06/11 P F006 ¢
Fix is available
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Document Information
Modified date:
07 July 2020