A fix is available
APAR status
Closed as program error.
Error description
Increase in DBM1 TCB times and dataset open / close activity after migrating to DB2 v10 CM9.
Local fix
N/A
Problem summary
**************************************************************** * USERS AFFECTED: DB2 users. * **************************************************************** * PROBLEM DESCRIPTION: Excessive dataset open/close activity, * * resulting in increased CPU time for the * * DBM1 address space. * **************************************************************** * RECOMMENDATION: * **************************************************************** The deferred close process (responsible for closing excess data sets when DSMAX has been exceeded) builds a large candidate list which it may continue using for a long period of time (several hours). Since this list is ordered by last-referenced time at the time the list was built, and the closing of candidates does not check to see if the reference time has changed, the order of closing datasets becomes less and less an LRU process the longer the list remains active. This may result in incorrectly closing datasets which are currently being frequently accessed, rather than others which are not currently being used. This may be particularly noticable if the list is built while one type of workload is being run (e.g. overnight batch jobs) but is still being used while another type of workload is being run (e.g. daytime online transactions).
Problem conclusion
The deferred close process has been modified to skip datasets on its candidate list which have been referenced since the time the list was built.
Temporary fix
Comments
APAR Information
APAR number
PM56725
Reported component name
DB2 OS/390 & Z/
Reported component ID
5740XYR00
Reported release
A10
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2012-01-25
Closed date
2012-03-27
Last modified date
2012-05-02
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UK77298 UK77309
Modules/Macros
DSNB1DRN
Fix information
Fixed component name
DB2 OS/390 & Z/
Fixed component ID
5740XYR00
Applicable component levels
Fix is available
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Document Information
Modified date:
02 May 2012