1. DB2 Memory management DB2 GSE 01/12/2011
14/11/2018
DB2 Memory management DB2 GSE 01/12/2011

2. Agenda Overview Statistics EDMPOOL DBDPOOL
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Agenda
Overview
Statistics
EDMPOOL
DBDPOOL
Dynamic Statement Cache (DSC)
Bufferpools
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3. Overview CF CF 14/11/2018 PLXA PLXB PLXB PLXC PLXC PLXT SYA1 SYA2 SYA3
MQP1
IMP1
DBP1
SYA2 CF
DBPI
MQP2
IMP2
DBP2 CF
SYA3
MQP3
IMP3
DBP3
SYA4
MQP4
IMP4
DBP4
SYA5
SYA6
SYA7
MQP7
IMP7
DBP7
SYA8
MQP8
IMP8
DBP8
PLXB
PLXB
SYB2 CF
MQC2
IMC2
DBC2
DBCF
SYB1
MQC3
IMC3
DBC3
MQC1
IMC1
DBC1
SYB7
MQC7
IMC7
DBC7
SYB8
MQC8
IMC8
DBC8
PLXC
PLXC
SYB2
SYC2 CF
MQC2
DBD2
IMC2
DBT2
DBC2
DBQ2
DBCF
DBI1
SYC1
MQQ1
IMQ1
DBQ1
MQC3
MQT1
IMC3
IMT1
DBC3
DBT1
MQC1
MQD1
IMC1
IMD1
DBC1
DBD1
SYC7
MQQ7
IMQ7
DBQ7
MQT7
IMT7
DBT7
MQD7
IMD7
DBD7
PLXT CF
SYT1
MQN1
IMN1
DBN1
DBZ1
SYT2
MQN2
IMN2
DBN2
DBN3
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4. Statistics SMF 100 Statistics trace records
14/11/2018
Statistics
SMF 100 Statistics trace records
Format and Load in DB2 tabel with BMC Mainview
Detail information (10 minute interval)
Summary by hour
System statistics
Buffer statistics
3 months history
Table field descriptions in User Guide
Additional descriptions in SDSNIVPD member DSNWMSGS
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5. EDMPOOL EDM Pools – V9 14/11/2018 TS / Mainframe Systems
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6. 14/11/2018
EDMPOOL
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7. 14/11/2018
EDMPOOL
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8. 14/11/2018
EDMPOOL
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9. 14/11/2018
EDMPOOL
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10. 14/11/2018
EDMPOOL
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11. 14/11/2018
EDMPOOL
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12. 14/11/2018
EDMPOOL
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13. Dynamic Statement Cache
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Dynamic Statement Cache
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14. Dynamic Statement Cache
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Dynamic Statement Cache
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15. 14/11/2018
DBDPOOL
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16. 14/11/2018
DBDPOOL
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17. EDMPOOL - DBDPOOL - DSC Triggers for critical problems:
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EDMPOOL - DBDPOOL - DSC
Triggers for critical problems:
EDMFAILS (QISEFAIL) : EDM pool full failures
SKELPOOLFULL (QISEKFAL) : SKELETON POOL FULL failures
STMTPOOLFULL (QISECFAL) : below the 2GB bar EDM pool statement cache full failures
STMTPOOLABFULL (QISESFAL) : above the 2GB bar EDM pool statement cache full failures
DBDPOOLFULL (QISEDFAL) : DBD pool full failures
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18. Bufferpools Main separation
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Bufferpools
Main separation
The first bufferpool by page size is for Catalog, Directory and DB2 Tools
The last bufferpool by page size is for Sort and Work
By Type AG
BNP
INFOCENTER
Application Tablespaces are in bufferpools with an even number
Application indexes are in bufferpools with an odd number
By Size
By access
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19. Bufferpools Initial setup 14/11/2018 TS / Mainframe Systems
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20. Bufferpools BP setup for specific reason 14/11/2018
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21. Bufferpools Data separation BP setup 14/11/2018 TS / Mainframe Systems
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22. Bufferpools Problems How to decide on random – Sequential
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Bufferpools
Problems
How to decide on random – Sequential
Growth of object
Changes in behavior
Difference in load
Example on BP3 – BP5
BP3 – pages – Index Random
BP5 – pages – Index Sequential > 30%
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23. Bufferpools Bufferpool Getpages 14/11/2018 TS / Mainframe Systems
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24. Bufferpools Bufferpool SYNC and ASYNC I/O BP3 –Index Random
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Bufferpools
Bufferpool SYNC and ASYNC I/O
BP3 –Index Random
BP5 –Index Sequential
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25. Bufferpools Desired Setup
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Bufferpools
Desired Setup
Only possible to change for Bufferpools based on data separation
In memory objects
Small objects
High getpage rate
No I/0 after first read
Hot spot objects
Objects with a high re-read factor (i.e. > 20 getpages/read)
Remaining objects
Specific Bufferpools
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26. Bufferpools How to move a object to another Bufferpool
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Bufferpools
How to move a object to another Bufferpool
DB2 table containing
list of objects
New Bufferpool
Current Bufferpool
Rexx procedure
Check objects that need to be changed
Check if they are in use
Issue STOP AT COMMIT
ALTER object
START OBJECT
CHECK for STOPP
Done during weekly maintenance window
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27. Bufferpools When moving objects verify impact Original Bufferpool
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Bufferpools
When moving objects verify impact
Original Bufferpool
New Bufferpool
Statistics for one index for one day:
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28. Bufferpools PAGEFIX Fix - Release is done when memory page is changed
14/11/2018
Bufferpools
PAGEFIX
Fix - Release is done when memory page is changed
High I/O intensity
Pages read = SYNC + ASYNC + GBP read
Pages written = SYNC + DEFERRED + GBP Write
Is activated or deactivated at bufferpool allocation
Up to 8% reduction
Disadvantage
Page can never be reused by any other process
Pages might be necessary for DUMP Processing
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29. Bufferpools Actions already done
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Bufferpools
Actions already done
Move some objects to best fitting Bufferpool
In memory Bufferpool BP7/BP8
PGSTEAL FIFO
Follow-up of I/O
PAGEFIX BP16 with pages
Merge two sets of Bufferpool
BP11 + BP13 each pages to one of
BP12 + BP14 each pages to one of
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30. Bufferpools Results of actions already done
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Bufferpools
Results of actions already done
Move objects to best fitting Bufferpool
Higher Getpage rate, 2500 to over 4000 a second at peak hours for in memory bufferpool BP7 with same size
In memory Bufferpool BP7/BP8
FIFO had no measurable CPU difference in applications due to divers workload
PAGEFIX BP16 with pages
no measurable CPU difference in applications due to divers workload
Merge two sets of Bufferpool
No impact seen in application Follow-up
small improvements/degradation for some Transactions
Improvements for batch with large workingset
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31. Bufferpools System page residency time
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Bufferpools
System page residency time
buffer pool size / total pages read per second
Random page residency time
Max
Bufferpool size * (1-VPSEQT/100) / sync pages read per second
More info can be found in the Redpaper DB2 9 for z/OS: Buffer Pool Monitoring and Tuning of Mike Bracey
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32. 14/11/2018
Bufferpools
Merge BP
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33. 14/11/2018
Bufferpools
Merge BP
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34. Bufferpools PAGEFIX BP16
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Bufferpools
PAGEFIX BP16
High I/O during peak period is more then 200 pages/sec
Not measurable due to workload
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35. 14/11/2018
Bufferpools
DATE HOUR BPGETPAGE BPREADS BPFPAGESRD BPPAGEINRD
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36. Questions ?
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