A fix is available
APAR status
Closed as program error.
Error description
GRECP recovery slow issue can be observed when start db command is used to recover lots of GRECP objects. One typical usage here is: START DB command is used to do GRECP recovery on DR site for GBP with AUTOREC set to N. With PI75286 applied, the auto-recovery GRECP retry threads(014.DRSTRT02) and the start db command threads(014.DRSTRT00) could have massive contentions with each other. In other words, a lots of timeouts and deadlocks. Hence slow down the GRECP recover process. Below messages could be found in the MSTR: . DEADLOCK: . DSNT375I -DB2B PLAN=BCT WITH 444 CORRELATION-ID=014.DRSTRT00 CONNECTION-ID=DB2B LUW-ID=DSNCAT.SYEC1B.D714FD3F1B1E THREAD-INFO=SYSOPR:*:*:*:*:* :*:* IS DEADLOCKED WITH PLAN= WITH CORRELATION-ID=014.DRSTRT02 CONNECTION-ID=DB2A LUW-ID=DSNCAT.SYEC1DB2.D714FCBBB35D THREAD-INFO=SYSOPR:*:*:*:*:* :*:* ON MEMBER DB2A DSNT501I -DB2B DSNILMCL RESOURCE UNAVAILABLE 445 CORRELATION-ID=014.DRSTRT00 CONNECTION-ID=DB2B LUW-ID=DSNCAT.SYEC1B.D714FD3F1B1E=0 REASON 00C90088 TYPE 00002007 NAME TESTTD .TESTTS4 .00000001 . TIMEOUT: . DSNT376I -PB6A PLAN=BCT CORRELATION-ID=014.DRSTRT02. CONNECTION-ID=PB6A LUW-ID=VTAM1.PB6ALU.D709DB7EB573 THREAD-INFO=SYSOPR:*:*:*:*:* :*:* IS TIMED OUT. ONE HOLDER OF THE RESOURCE IS PLAN= WITH CORRELATION-ID=014.DRSTRT00 CONNECTION-ID=PB6A LUW-ID=VTAM1.PB6ALU.D709DB2E6A8C THREAD-INFO=SYSOPR:*:*:*:*:* :*:* ON MEMBER PB6A DSNT501I -PB6A DSNILMCL RESOURCE UNAVAILABLE 328 CORRELATION-ID=014.DRSTRT02 CONNECTION-ID=PB6A LUW-ID=VTAM1.PB6ALU.D709DB7EB573=0 REASON 00C900BA TYPE 00002001 NAME TESTDB .TESTTS .00000001
Local fix
BYPASS/CIRCUMVENTION: 1.)start db2 in MAINT mode to run START DB command. In MAINT mode, the 014.DRSTRT02 will not be started. 2.)use AUTOREC=YES for GBP. Db2 will recover most GRECP objects automatically right after the Db2 restart complete.
Problem summary
**************************************************************** * USERS AFFECTED: * * All Db2 for z/OS users. * **************************************************************** * PROBLEM DESCRIPTION: * * Frequent drain timeouts occur during * * the DRSTRT02 recovery process for * * objects with a group bufferpool set as * * AUTOREC(NO). * **************************************************************** * RECOMMENDATION: * * Apply corrective PTF when available * **************************************************************** If a manual GRECP recovery is started to recover objects marked as such, frequent drain timeouts can occur with auto GRECP recovery even if the object's group bufferpool is set to AUTOREC(NO). The DRSTRT02 routine would check for objects marked GRECP and attempt to recover those objects. However, it did not check their group bufferpools to make sure that auto recovery was on until after it acquired a drain. Once it detected that auto recovery was disabled, it would not dedrain before proceeding to the next object, possibly causing the drain to be held for a long time as drains for other objects are acquired. In this scenario, acquiring a drain is a costly process considering that no recovery is being done on the object.
Problem conclusion
Logic for the DRSTRT02 routine was modified so that it would check if the object's group bufferpool had auto recovery enabled before a drain is acquired to proceed with the GRECP recovery.
Temporary fix
Comments
APAR Information
APAR number
PH19639
Reported component name
DB2 OS/390 & Z/
Reported component ID
5740XYR00
Reported release
B10
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2019-11-26
Closed date
2020-02-27
Last modified date
2020-04-02
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI68125 UI68126
Modules/Macros
DSNB1PCK DSNISREC
Fix information
Fixed component name
DB2 OS/390 & Z/
Fixed component ID
5740XYR00
Applicable component levels
Fix is available
Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.
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Document Information
Modified date:
10 March 2020