ims performance hints and tips - ims ug august 2012 sao paulo
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1 © 2012 IBM Corporation
August 2012 IMS User Group, Sao Paulo, Brazil
IMS Performance Hints and Tips
Mike GonzalesIBM Software Group
2 © 2012 IBM Corporation
2012 IMS Technical Conference , Australia
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© Copyright IBM Corporation 2012. All rights reserved.U.S. Government Users Restricted Rights - Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
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Disclaimer
3 © 2012 IBM Corporation
2012 IMS Technical Conference , Australia
Part 1 : The Mechanic’s Tool Kit
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2012 IMS Technical Conference , Australia
Log Analysis Tool(s)
• Standard Utilities
– DFSERA10
– DFSILTA0
– DBFILTA0
– DFSISTS0
• KBLA (pre IMS V12)
• IMS Performance Analyzer
• IMS Problem Investigator
• IBM Transaction Analysis Workbench
• Set TRANSTAT=Y
– (DFSDFxxx, TRANSACT macro, CREATE/UPD TRAN/PGM)
– Enhanced transaction statistics
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2012 IMS Technical Conference , Australia
Sampling Tool
• IBM Application Performance Analyzer
• Macro 4 Freeze Frame
• Compuware STROBE
• IBM MVS Hardware Instrumentation Service (HIS)
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System Resource Reporting
• IBM Resource Measurement Facility (or equivalent)
• Tivoli Decision Support (TDS) for IMS
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2012 IMS Technical Conference , Australia
Part 2 : Infrastructure – The Chasis
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2012 IMS Technical Conference , Australia
MVS Workload Manager (WLM)
• Limit service periods to 30 or fewer
• Use all 6 Importance values (1 to 5, + Discretionary)
• Limit use of CPU Critical
• Define IMS transaction response time goals for IMS TM
• Use common service classes for multiple subsystems
• Use report classes for granular feedback/charge back
• Target Performance Index 0.8 – 1.1 during peaks
• Service Coefficients : CPU 1.0 SRB 1.0 MSO 0.5 IOC 0.0
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2012 IMS Technical Conference , Australia
Global Resource Serialization (GRS)
• Convert RECON RESERVEs to ENQs in GRS STAR
• Exclude RECONs for access outside of a parallel sysplex
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Resource Access Control Facility (RACF)
• Cache, cache, cache
– VLF
– CF
– IMS OTMA
– IMS Connect
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2012 IMS Technical Conference , Australia
Part 3 : IMS – The Engine
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2012 IMS Technical Conference , Australia
IMS Scheduling – Program Load
• Program Preload
– APA – Load Module Summary
– STROBE – SVC122 count
– PRLD=suffix of DFSMPLxx
• Library Routine Retention (LRR) – DFSINTxx+CEELRRIN or CEELRRXP
• Add IMS program libraries to VLF (stores load modules in data spaces)
• LLA – FREEZE (manages TTR/directory information, FREEZE ensures they
remain in virtual storage)
• STEPLIB the application
program libraries
that are in LINKLIST
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2012 IMS Technical Conference , Australia
IMS Scheduling – Scheduling Blocks/Pools
• Resident PSB/DMB – loaded during IMS initialization
• Size pools to avoid cast outs
• PWFI – reuse scheduled resources, maximize local-first
scheduling in shared queues
• IFPs – Schedule once per region execution
• BMPs – WFI and looping/waiting schedule once
• PST=xxx
– Set high enough to prevent excessive GETs/FREEs
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2012 IMS Technical Conference , Australia
IMS Scheduling – Shared Queues False Scheduling
• CFCC 16 reduces global false scheduling with multiple
members in a shared queues group
• IMS V11 reduces local false scheduling between parallel regions
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2012 IMS Technical Conference , Australia
IMS Page Fixing
• DFSFIXnn
– FP, DMBD, PSBD, DLDP, DLMP, DPSB, QBUF
– V12 backs 31-virt with 64-real for DBWP, DLDP, DLMP, DPSB, and PSBW
• DB Buffers – specify fix options in DFSVSMxx
• Watch out for SORT !!!
– Consider WLM Storage Critical for DB2 DBM1
• EXVR=1
– Page fix Queue Buffers
• EXCPVR=1
– Page fix OSAM buffer pool
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2012 IMS Technical Conference , Australia
IMS Database Locking
• Use Program Isolation as long as possible
• With IRLM :
– use SCOPE=NODISCON
� Prevent batch connect/disconnect when IMS control region is down
– Use DEADLOK > 5
� Use millisecond based detection cycles
• Use LOCKTIME (DFSVSMxx/DFSVSAMP)
� Sets timeout for waiting on lock request
� Return ‘BD’ or U3310
• Use minimum PROCOPT needed
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2012 IMS Technical Conference , Australia
IMS Database Access Methods
• Performance by design
– DEDB
– HDAM/PHDAM – OSAM
– HDAM/PHDAM - VSAM
– HIDAM/PHIDAM – OSAM
– HIDAM/PHIDAM – VSAM
• DEDB + Secondary Index
– HDAM/PHDAM + Secondary Index
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2012 IMS Technical Conference , Australia
IMS Database Buffers
• Adjust to workload, alter dynamically (IMS V12)
• Page fix if not storage constrained
• IMS Buffer Pool Analyzer
– Use buffer life as tuning metric
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2012 IMS Technical Conference , Australia
IMS Logging
• IMS V12 OLDS/SLDS Striping
• Adjust log buffers to avoid buffer waits
• Use 64-bit buffer pool (OLDS BLKSIZE = 4K * n)
• WADS mirroring max 20 Km
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2012 IMS Technical Conference , Australia
IMS Logging - 64-bit Log Buffers / 1M pages
• IEASYSxx
– LFAREA=nn (%, G, or M)
• OLDS allocated by DFSMS
– Extended format (striped)
• DFSVSMxx
– BUFSTOR=64
– BLKSZ=(4K * n)
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2012 IMS Technical Conference , Australia
IMS Queue Buffers
• Adjust number to prevent QBUF waits
• Size according to majority of queue activity
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2012 IMS Technical Conference , Australia
IMS Connect
• Persistent socket
– Connect once then multiple write/read iterations for multiple transactions before Close (Disconnect)
– This will keep the socket open – make sure you have defined enough sockets
• Send ICON messages as a single message with all
components
• Ensure TCPIP NODELAYACK is specified on TCP/IP
PORT or GATEWAY statements
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2012 IMS Technical Conference , Australia
zIIP/zAAP support
• Request response processing for authorized CQS clients is
eligible to run on a zIIP
• Examples
• When the IMS control region is running with IMS Shared
Message Queues or Shared IMS Fast Path Message Queues
enabled
• When the IMS Resource Manager address space is using a
resource structure
• IMS Java runs on zAAPs
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Part 4 : Outside the Box – The Accessories
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WMQ
• Tune MQ buffers and pagesets
• Review and disable internal traces
• Consider MQGET(WAIT) loop if IMS Msg Queues not needed
• Preload WMQ routines in MPRs
– CSQQDEFV, CSQQCONN, CSQQDISC, CSQQTERM, CSQQINIT, CSQQBACK, CSQQCMMT, CSQQESMT, CSQQPREP, CSQQTTHD, CSQQWAIT, CSQQNORM, CSQQSSOF, CSQQSSON, CSQFSTAB,CSQQRESV, CSQQSNOP, CSQQCMND, CSQQCVER, CSQQTMID, CSQQTRGI, CSQFSALM, CSQAPRH
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2012 IMS Technical Conference , Australia
DB2
• DB2 thread counts – make sure enough storage for DB2
• Reduce/prevent global contention
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2012 IMS Technical Conference , Australia
RRS
• Avoid RRS
• Monitor and resize DELAYED UR logstream to avoid
offloads
• IMS V12 XCFIMS for Commit Mode 1 instead of RRS
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2012 IMS Technical Conference , Australia
CICS - DBCTL
• IMS V12 DRA Open Thread TCB – CICS Threadsafe
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2012 IMS Technical Conference , Australia
Contact Information
For assistance or service engagement requests contact:
Jeff Hook, Manager IMS Technical Services
Mike Gonzales, IMS Technical Specialist