A fix is available
APAR status
Closed as new function.
Error description
Db2 11 and Db2 12 for z/OS new function
Local fix
n/a
Problem summary
**************************************************************** * USERS AFFECTED: * * All users of Db2 11 for z/OS and Db2 12 for * * z/OS who use IBM Db2 Analytics Accelerator * **************************************************************** * PROBLEM DESCRIPTION: * * In our current implementation, if a Db2 * * system is paired to a mixture of V5 and * * V7 accelerators, and if a query is * * eligible to be accelerated to both V5 * * and V7 accelerators (i.e., the table is * * accelerated on all accelerators), the * * Workload Balance (WLB) algorithm will * * balance the query acceleration within * * only one version of accelerators. * * It will choose either a V7 or V5 * * accelerator based on the setting of * * option 8 (FAVOR NEW ACCELERATOR_TYPE) * * of the QUERY_ACCEL_OPTIONS subsystem * * parameter. However , the workload * * balancing algorithm select an * * accelerator based on the workload * * comparison within one version of * * accelerators, not between different * * versions of accelerators. * * For customers that have both V5 and V7 * * accelerators paired and prefer queries * * to be accelerated based on the workload * * on each accelerator between different * * versions, the WLB algorithm will be * * adjusted so a query can be accelerated * * to a V5 or V7 accelerator based on the * * workload comparison on all accelerators * * from different versions. * * To support customers who want the * * ability to balance query acceleration * * between both V5 and v7 accelerators * * based on workload volume and who want * * the ability to control this workload * * balancing behavior, a new option * * (10 BALANCE WORKLOAD BETWEEN VERSIONS) * * is being added to the existing * * QUERY_ACCEL_OPTIONS subsystem * * parameter. * * Important: The CURRENT ACCELERATOR * * special register and the ACCELERATOR * * bind option take precedence over the * * BALANCE WORKLOAD BETWEEN VERSIONS * * subsystem parameter with regards to * * workload balancing. * * For example, when the CURRENT * * ACCELERATOR special register or the * * ACCELERATOR bind option specifies * * a particular accelerator, workload * * will be offloaded only to that * * accelerator if it is available. * * In this situation, workload will not * * be offloaded to another accelerator, * * regardless of version, even if * * BALANCE WORKLOAD BETWEEN VERSIONS is * * set to YES. * * * * In Db2 11 for z/OS only, queries might * * be offloaded to a different accelerator * * when the V7 accelerator specified in * * CURRENT ACCELERATOR special register or * * ACCELERATOR bind option is available. * **************************************************************** * RECOMMENDATION: * * Apply corrective PTF when available. * **************************************************************** If a Db2 system is paired to a mixture of V5 and V7 accelerators and a query is eligible to be accelerated to both V5 and V7 accelerators (i.e., the table is accelerated on all), the Workload Balance (WLB) algorithm will choose an accelerator based on the workload comparison within only one version of accelerators. It will choose either a V7 accelerator or V5 accelerator based on the setting of option 8 (FAVOR NEW ACCELERATOR_TYPE) of the QUERY_ACCEL_OPTIONS subsystem parameter. To support customers who want the ability to balance query acceleration between both V5 and v7 accelerators based on workload volume and who want the ability to control this workload balancing behavior, a new option 10 (BALANCE WORKLOAD BETWEEN VERSIONS) is being added to the existing QUERY_ACCEL_OPTIONS subsystem parameter. This PTF adds a new BALANCE WORKLOAD BETWEEN VERSIONS option to the subsystem parameter QUERY_ACCEL_OPTIONS to Db2 in DSN6SPRM: - 10 : Specifies that Db2 will balance query acceleration according to the actual workload of each available query accelerator between different versions (V5/V7). If option 10 is specified on any member of a data sharing environment, it is recommended to specify option 10 on all members. Important: The CURRENT ACCELERATOR special register and the ACCELERATOR bind option take precedence over the BALANCE WORKLOAD BETWEEN VERSIONS subsystem parameter with regards to workload balancing. For example, when the CURRENT ACCELERATOR special register or ACCELERATOR bind option specifies a particular accelerator, workload will be offloaded only to that accelerator if it is available. In this situation, workload will not be offloaded to another accelerator, regardless of version, even if BALANCE WORKLOAD BETWEEN VERSIONS is set to YES. In Db2 11 for z/OS only, queries might be offloaded to a different accelerator when the V7 accelerator specified in CURRENT ACCELERATOR special register or ACCELERATOR bind option is available.
Problem conclusion
Temporary fix
Comments
Acceleration behavior is being changed so that queries can be accelerated on any supported accelerator, regardless of version, based on workload volume. Prior to this change, workload balancing for accelerated queries was limited to only a single accelerator version, either V7 or V5. A new option 10 (BALANCE WORKLOAD BETWEEN VERSIONS) is being added to the existing QUERY_ACCEL_OPTIONS subsystem parameter, which allows customers to control query acceleration based on workload comparison across all supported versions of accelerators. Additionally, Db2 11 for z/OS is being modified to use the accelerator that has been specified CURRENT ACCELERATOR special register or in the ACCELERATOR bind option, if that specified accelerator is available. Additional Keywords: IDAAV4R1/K IDAAV5R1/K IDAAV7R1/K
APAR Information
APAR number
PH05477
Reported component name
DB2 OS/390 & Z/
Reported component ID
5740XYR00
Reported release
B10
Status
CLOSED UR1
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2018-11-19
Closed date
2019-08-29
Last modified date
2019-10-01
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI65060 UI65061
Modules/Macros
DSNWZIFB DSNWZIFC DSNTIP8A DSNDQWPZ DSNX8WAC DSNTINST DSNDSPRM DSN6SPRM
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:
01 October 2019