A fix is available
APAR status
Closed as unreproducible in next release.
Error description
Automatic bufferpool management using WLM support does not work.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All users of DB2 for z/OS. * **************************************************************** * PROBLEM DESCRIPTION: Delivery of DB2 9 for z/OS WLM Buffer * * Pool Management and enabling of DB2 * * WLM Delay Monitoring Support * **************************************************************** * RECOMMENDATION: * **************************************************************** When DB2 9 for z/OS was made generally available, its announced support for z/OS 1.8 WLM Buffer Pool Management capability was disabled. The DB2 WLM delay monitoring capability was also disabled prior to general availability of DB2 9 for z/OS by APAR PK34179.
Problem conclusion
Temporary fix
Comments
The DB2 9 for z/OS support for z/OS V1R8 WLM buffer pool management capability is now available for use. This capability is activated for a buffer pool when a buffer pool is defined or altered by the ALTER BUFFERPOOL command with the AUTOSIZE option set to YES. Each time DB2 processes an ALTER BUFFERPOOL command against a buffer pool that already has the AUTOSIZE(YES) attribute or is being altered to have the AUTOSIZE(YES) attribute, DB2 will register the buffer pool with WLM. In the registraton of the buffer pool with WLM, DB2 will use the current defined size of the buffer pool or the size specified with the VPSIZE option of the command as the buffer pool's initial size and DB2 will use this initial size to calculate a maximum size and a minimum size for the buffer pool which are also told to WLM during the registration request. The maximum size of a buffer pool will be calculated to be 1.25 times the initial size and the minimum size of a buffer pool will be calculated to be 0.75 times the initial size. As a CICS, IMS, or distributed task executes, DB2 will report to WLM that a delay has occurred to the task due to a DB2 buffer pool I/O wait. A buffer pool I/O wait occurs when a task has to wait for a buffer pool page to be read into memory. This is called a synchronous database I/O wait. When WLM has to decide on a policy adjustment, it looks at the various service classes that have been used to manage work. If any of those service classes have not met their performance goals (i.e. the performance indicator (PI) of the service class is greater than 1), WLM then analyzes the various delays that have been tracked against the service class, and if a large portion of the delays had been due to buffer pool I/O waits for a particular buffer pool, WLM may trigger an alter to the size of the buffer pool. When this occurs, a DB2 message, DSNB555I, will be issued stating that a buffer pool is being changed from its current size to a new size. The setting of the buffer pool to the indicated new size is processed by DB2 as if an ALTER BUFFERPOOL command was issued but DB2 does not reregister the buffer pool with WLM. Thus, the buffer pool's new size will become the buffer pool's initial size when the buffer pool is reallocated after previously being deleted. When DB2 deletes a buffer pool because it is no longer needed, it will deregister the buffer pool from WLM. During buffer pool reallocation, DB2 will reregister the buffer pool with WLM but the maximum and minimum sizes will be based on the new size of the buffer pool. WLM can issue a change which either increases or decreases the size of a buffer pool. A buffer pool could be decreased in size if WLM observes that available real storage is being severely over-committed. The z/OS WLM APAR, OA18461, should also be applied so that WLM will request that a DB2 buffer pool be altered. This APAR also restores general DB2 WLM delay monitoring support. **Urgent, Please Read** Please apply z/OS WLM APAR OA32631 to avoid Spin Loops with AUTOSIZE(YES)04E RC00E20003 DSNSVBK +05EA . EXCESS REPT BLOCKS
APAR Information
APAR number
PK75626
Reported component name
DB2 OS/390 & Z/
Reported component ID
5740XYR00
Reported release
910
Status
CLOSED UR1
PE
NoPE
HIPER
NoHIPER
Special Attention
YesSpecatt / New Function
Submitted date
2008-11-13
Closed date
2009-12-26
Last modified date
2010-11-05
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UK53198
Modules/Macros
DSNB5WRA DSNDACOM DSNDDBPB DSNDSSCA DSNLAGNT DSNLCRTD DSNLCRTR DSNLIRTR DSNLTACT DSNLTZCH DSNTSTRT DSNVAI DSNVDBPB DSNVDBPM DSNVRMIM DSNVSDC0 DSNVSR DSNVSRR DSNVSRRX DSNVSRT DSNVSRX DSNXECPD DSNXERD DSNYASCP DSN3CT30 DSN3CT80
Fix information
Fixed component name
DB2 OS/390 & Z/
Fixed component ID
5740XYR00
Applicable component levels
R910 PSY UK53198
UP10/01/13 P F001
Fix is available
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Document Information
Modified date:
05 November 2010