Notification
Risk classification
Red Alert
Risk categories
Data Loss
Affected Domain
All Db2 V12 z/OS data sharing users of Partition-By-Range (PBR) Relative Page Numbering (RPN) table spaces with PTF UI92688 applied or Db2 V13 z/OS data sharing users of PBR RPN table spaces with PTF UI92689.
Abstract
With APAR PH54949 - UI92688/UI92689 applied, PBR RPN table spaces in V12 and V13R1M100 can take advantage of a new lock algorithm to reduce false lock contention in data sharing. Due to a code defect, migration of a member from V12 to V13R1M100 or activation of a function level V13R1M500 or higher from V13R1M100 can result in the simultaneous use of different locking algorithms on different members of a data sharing group for the same pageset which can result in page regression, undetected data loss and/or Db2 transaction abends.
For further information regarding external symptoms see APAR PH61633.
Description
APAR PH54949 - UI92688/UI92689 retrofitted a locking enhancement for PBR RPN table spaces from V13 to V12. This change contains a defect which can cause the new lock algorithm to be used in V12 but the old algorithm to be used by a member started with V13R1M100. Conversely, it is possible that the old algorithm is used by a member in V13R1M100 but another member uses the new algorithm once V13R1M500 or above is activated. The simultaneous use of different locking algorithms on different members of a data sharing group for the same pageset can result in page regression, undetected data loss and/or Db2 transaction abends. Both PTFs for PH54949 are marked in error and will be fixed by PH61633.
IBM projects that a ++APAR fix for PH61633 is expected to be available by June 28th, 2024 with PTF availability in July.
This issue only applies to data sharing environments with PBR RPN table spaces when migrating from V12 to V13R1M100 or activating V13R1M500 or higher from V13R1M100 and if V12 PTF UI92688 or V13 PTF UI92689 is or was applied. Removing UI92688 or UI92689 does not eliminate exposure to this issue.
Recommended Action
No action is required if any of the following are true:
- The system is non data sharing.
- The Db2 environment does not contain any PBR RPN table spaces.
- V12 PTF UI92688 and/or V13 PTF UI92689 have never been applied to any member of the data sharing group.
Otherwise, IBM recommends the following actions based on the version of your Db2 data sharing group:
- For Db2 data sharing groups exclusively on V12
- No current exposure exists. Do not migrate to V13 until the PTF for PH61633 is applied to all members of the V12 group and actions specified in the PTF ++HOLD have been taken. It is not necessary to shut down the entire group to apply the PTF for PH61633.
- For Db2 data sharing groups exclusively on V13R1M100
- No current exposure exists. Do not activate function level V13R1M500 or higher until the PTF for PH61633 is applied to all members of the group and actions specified in the PTF ++HOLD have been taken. Do not fall back to V12 unless the PTF for PH61633 is applied to V12. It is not necessary to shut down the entire group to apply the fix for PH61633.
- For Db2 data sharing groups in co-existence, i.e. a mix of V12 and V13 members
- To eliminate exposure to this issue it is necessary to either migrate remaining V12 members to V13 or for V13 members to fall back to V12. Once this is done, follow the prior applicable instructions for the respective version.
- For DB2 data sharing groups at function level V13R1M500 or above
- To eliminate exposure to this issue, REORG each PBR RPN partition or alternatively use the -STOP DATABASE and -START DATABASE commands to stop and start every data partition and index space on a PBR RPN table space. It is not necessary to reorganize all partitions of the PBR RPN table space simultaneously. Alternatively, the V13 fix for PH61633 can be applied to all members of the group. It is not necessary to shut down the entire group to apply the fix for PH61633.
Date first published
21 June 2024
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Document Information
Modified date:
21 June 2024
UID
ibm17158065