copyright © 2003 best customer solutions, inc.1 z/os release 4 migration: performance tips and...

Copyright © 2003 Best Customer Solutions, Inc.

1

z/OS Release 4 Migration: Performance Tips and Gotchas

Search390.com Webcast

Jim Schesvold

Best Customer Solutions, Inc.

[email protected]

http://www.mainframehelp.com

Copyright © 2003 Best Customer Solutions, Inc. 2

AGENDA

• Criteria & Format• Virtual Storage Topics• WLM Topics• JES2 Topics• DFSMS Topics• Miscellaneous Topics• Q&A• This is a tongue-twister!


CRITERIA & FORMAT• Focus is on a “vanilla” migration and what

performance issues might arise as a consequence• This includes possible hardware changes (upgrades)• Releases covered -- OS/390 V2R9 through z/OS

V1R4• Release is identified wherever possible

– PTF may be retrofitted to prior releases

• Does not include implementation of new function (64-bit, hipersockets, etc.)

• This is not a tuning presentation

• Grouped by VS, then z/OS element• Reference material is identified

– Hiperlinks are active on Slide Show


VIRTUAL STORAGE


SQA SHORTAGE DETECTION• APAR OW54022 replaces OW50225 as of 6/5/2002• OW50225

– Changes detection levels, does not relieve shortage– Thresholds are used to notify SRM of a CSA shortage– SQA Shortage (IRA100E) changed from 32K to 512K– Critical SQA Shortage (IRA101E) changed from 16K to 128K– Invokes storage recovery routines earlier during depletion– Can cause unnecessary IRA100E, IRA101E messages

• OW54022– Released to address unnecessary messages problem– Cuts threshold sizes in half– Provides mechanism to change threshold values

• Change IGVDCLIM CSECT constants in IEAIPL04

• OW50225 includes an approach to identify cause


SQA SHORTAGE DETECTION

• Effective Version– OS/390 V2R10– See APAR for correct PTF

• References– For all APARS in this webcast, visit IBM Technical Support

Search, at http://www-1.ibm.com/support/search/index.html , then use the APAR number as the search keyword

– Hiperlink will be IBM Technical Support Search for the rest of the slides

– z/OS & OS/390 Performance Hot Topics, Kathy Walsh, p. 6, at ftp://ftp.software.ibm.com/software/mktsupport/techdocs/hot02.pdf


PDSE ECSA REDUCTION• Moves PDSE control blocks from ECSA to new

SMSPDSE Address Space– Between 1K and 2K per MEMBER– 1,000’s of members = Megabytes of ECSA– IEBCOPY or user BLDL programs access all members at 1

time

• SMXC and SYSBMFAS processing has also been moved to SMSPDSE

• End Of Memory processing now uses Cancel code– Higher PDSE reliability after user Address Space is forced

• Available via APAR OW53235 plus multiple child APARs– Visit IBM Support and search on UW99418– PDO service type put tape for PDSE, see II13336

• More relief is to come, see II12791


PDSE ECSA REDUCTION

• Effective Version– OS/390 V2R10– UW99418 for z/OS V1R3 and V1R4– UW99417 for OS/390 V2R10, z/OS V1R1 and z/OS V1R2

• References– IBM Technical Support Search, use APAR # or PTF # as

search keyword– Migrating to z/OS V1R4 - Parts 1 and 2, Marna Walle, p. 98, at

http://docs.share.org/proceedings/sh100/s2871.pdf

– z/OS V1R4 Migration Guide, at http://publibfp.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/e0z2m101/10.3.1


TCP/IP & VTAM• PQ52813 - ECSA, ESQA Shortage due to IPMAIN

contention• OA01756, OA01656 - CSA, ECSA, TIBUF growth• OW52758 - SP 231 Key 6 growth exhausts CSA• II11553, II12658 - TCP/IP storage, TCP/IP CSM APAR

index• II13442 - VTAM CSM APAR index

– Includes technique for coding IVTPRM00

• Effective Version - OS/390 V2R10 & up depending on PTF

• References– IBM Technical Support Search, use APAR # as keyword– z/OS & OS/390 Performance Hot Topics, Kathy Walsh, p. 16, at

ftp://ftp.software.ibm.com/software/mktsupport/techdocs/hot02.pdf


z/ARCHITECTURE ESQA• 64-bit and z/Series (with z/OS) go hand in hand

– Bimodal Migration Accommodation offering = 6 month cutover

• OW56566 - ESTOR ESQA no longer exists– Allocated at IPL for ESTOR mgt., residual portion available– Reduction is about 8M ECSA per 1G of ESTOR

• If ESQA/ECSA is tight, this could cause a shortage• Can cause S878 & S80A abends, or wait state• Effective Version - OS/390 V2R10 with z/Series • References

– IBM Technical Support Search, use OW56566 as keyword– z/OS & OS/390 Performance Hot Topics, Kathy Walsh, p. 6,

at ftp://ftp.software.ibm.com/software/mktsupport/techdocs/hot02.pdf

– z/OS V1R4 Migration Guide, at http://publibfp.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/e0z2m101/2.2.15


OTHER VS ITEMS• OW53508 - SMS SQA/CSA storage creep (OS/390 V2R10)

– Due to UCB capture w/Dynamic IO Configuration Environment– IBM Technical Support Search, use OW53508 as keyword

• Switchable, namable TSO Broadcast Data Set (z/OS V1.3)– Unavailability of SYS1.BRODCAST could deplete CSA– z/OS V1R4 Migration Guide, at http://publibfp.boulder.ibm.com/cgi-bin/

bookmgr/BOOKS/e0z2m101/5.2.6

– z/OS 1.3 User Experiences at Boeing, Deborah Barnes, p. 19, at http://www.share.org/proceedings/sh99/SHARE/data/S2868b.pdf

• Review Virtual Storage settings (all releases)– z/OS V1R4 Migration Guide, at http://publibfp.boulder.ibm.com/cgi-bin/

bookmgr/BOOKS/e0z2m101/2.2.10

– z/OS V1R4 Planning for Installation, at http://publibfp.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/e0z2b132/6.3.6

– z/OS V1R4 MVS Initialization & Tuning Guide, at http://publibfp.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/iea2e110


WORKLOAD MANAGER


VELOCITY CALCULATION• OW47277 (z/OS V1R1)

– Calculations are changed for:• LPAR CPU Management inequities• Softcapping, especially responsiveness

– This may lower velocities for systems running in LPAR mode– Velocity goals may need to be lowered as a result– OW48268, OW55665 have multiple fixes, minimize velocity

impact– OW57249 fixes S0C9 when COMPAT is used

• Can be key when running a sysplex with both OS/390 & z/OS

– Execution Velocity Migration Tool can be found at http://www.ibm.com/servers/eserver/zseries/zos/wlm/tools/velocity.html

• References– IBM Technical Support Search, use APAR # as keyword– Cheryl Watson’s Hot Flashes #9, pp. 17-18, at



INITIATOR PRIORITY• OW55344 (OS/390 V2R10)

– INIT priority is set via PVLDP in IEAIPSxx for COMPAT– Originally, INITs ran in SYSSTC service class for GOAL

• Dispatching priority was fixed at 254

– When CPU intensive exits run before job select under an INIT, it runs at priority 254; this can interfere w/online, other key work

– OW55344 adds INITIMP parameter in IEAOPTxx that sets dispatching priority of SYSSTC, plus writeup on how to use it

• OA03581 fixes OW55344– If not using INITIMP, last batch priority is used versus 254– Circumvention is to set INITIMP (0, 1, 2, 3, or E, not priority)

• References– IBM Technical Support Search, use APAR # as keyword– Cheryl Watson’s Hot Flashes #9, p. 19, at

http://docs.share.org/proceedings/sh100/s2543. pdf


FEWER, FASTER CP’S• Moving to a processor w/fewer, faster CPs

– High priority, single-TCB (or close to it, like CICS) applications can now consume more of a processor’s capacity

– This is a problem when that’s not the objective

• WLM can control high priority, single-TCB application– For COMPAT, use time slicing (TSPTRN in IEAIPSxx)– GOAL mode uses performance objectives within a service policy– Resource Groups can provide even more control

• References– Cheryl Watson’s Hot Flashes #9, p. 19, at


– Performance When Moving to Fewer, Faster CPs, Walt Caprice Jr., at http://www.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/WP100258

– Cheryl Watson’s Tuning Letter - 1998, No. 6: Sizing Processors, pp. 14-23, at http://www.watsonwalker.com/tl9806.pdf


OTHER WLM ITEMS• Do not define WLM softcapping unless it’s used (z/900)

– This is specified on LPAR Change Logical Partition Controls panel– Performance, throughput problems may arise– WLM Soft Capping for Sub Capacity Pricing, Kathy Walsh, at

http://www.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/Flash10099

• OW47667 - Remove I/O disconnect time from velocity formula if using I/O priority management (OS/390 V2R8)– This increases velocity due to non-productive time– IBM Technical Support Search, use APAR # as keyword– WLM Implications W.R.T. APAR OW47667, Jim McCoy, at

http://www-1.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/Flash10101

– z/OS & OS/390 Performance Hot Topics, Kathy Walsh, p. 10, at ftp://ftp.software.ibm.com/software/mktsupport/techdocs/hot02.pdf


JES2


$#POST WITH $#BUSY

• $#BUSY macro is enhanced to include $CKPT (if appropriate) and $#POST when BUSY=OFF (z/OS V1R4)

• $#BUSY sets/tests busy indicator for job output element• If you already have coded $#POST (as you should, but

many didn’t), you now execute 2 $#POSTs• $#POST is a costly call• Existing $#POST should be removed• References

– z/OS V1R4 Migration, at http://publibfp.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/e0z2m101/13.2.21

– z/OS V1R4 JES2 Migration, at http://publibfp.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/has2e130/5.1.7.1

– z/OS V1R4 JES2 Macros, at http://publibfp.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/has2c220/CCONTENTS


OTHER JES2 ITEMS

• OA02686 - High CPU using HASPPSO (z/OS V1R4)– ISV External Writer packages like SAR, QSERV, etc. use PSO interface– Also see IBMLINK item RTA000053488 (20% increase fixed with tuning)

• OW54137 - High CPU using SYSOUT application programming interface (SAPI) (z/OS V1R4)– Improper handling of invalid Job Output Element (JOE)– Occurs after system crash or JES2 error– SAPI application appears to be hung

• OW55693 - Slow JES2 processing w/IXCQUERY (z/OS V1R4)– IXCQUERY -- Obtain XCF Information (Sysplex service to Coupling

Facility Structure)– Apply fix or run JES2 checkpoint on DASD

• References– IBM Technical Support Search, use APAR # as keyword


DFSMS


VSAM INDEX CISIZE• Size calculation has changed (z/OS V1R3)

– Size may increase; for example from 1536 to 2560– Can increase LSR storage requirements, in some cases up to 30%– LSR pools may need to be redefined, both buffer and buffer pool size(s)– CICS VSAM files, IMS databases may be affected– The change attempts to improve the chance an index record represents

all data Control Intervals in a data Control Area

• References– z/OS V1R4 Migration, at http://publibfp.boulder.ibm.com/cgi-bin/bookmgr

/BOOKS/e0z2m101/10.1.2

– z/OS V1R3 DFSMS: Using Data Sets, at http://publibfp.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/dgt2d410/2.5.1.3

– Search390.com: Ask The Expert, Jim Schesvold, at http://search390.techtarget.com/ateQuestionNResponse/0,289625,sid10_cid514970_tax292523,00.html

– VSAM Cluster Index CI Size Calculation Change, Charlie Burger, at http://www-1.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/Flash10206


DFSMSdss COPY• OW55383 - Improved FULL Volume COPY Performance

(OS/390 V2R10) – Specifying ADMINISTRATOR, ALLDATA(*), ALLEXCP bypasses read of

source VTOC tracks– Specifying ADMINISTRATOR, PURGE bypasses read of the target VTOC– Specifying ADMINISTRATOR, ALLDATA(*), ALLEXCP, PURGE bypasses

read of both source and target VTOC tracks– The larger the VTOCs, the greater the improvement– Improvement is greatest when using FlashCopy or SnapShot

• References– DFSMSdss Full volume Copy Performance Enhancement, Charlie Burger,

at http://www.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/Flash10206

– IBM Technical Support Search, use OW55383 as keyword– z/OS V1R3 DFSMSdss Storage Administration Reference, at http://

publibfp.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/DGT2U211/7.4.3 & http://publibfp.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/DGT2U211/7.4.4


VSAM Striped Data Sets

• OW50528 - Secondary space allocation performance improvement – Extents are now released on primary volume at VSAM

RESET– Guaranteed space data sets will release extents on

guaranteed space volumes if not part of primary allocation

– KSDS index component will also be reset– Striped data sets can now also use REUSE

• OW51353 - Fixes OW50528 problem with REUSE and IMBED

• References– IBM Technical Support Search, use APAR # as keyword– Migrating to z/OS V1R4 - Parts 1 and 2, Marna Walle, p. 122, at



MISCELLANEOUS ITEMS


GRS WILDCARD SUPPORT• OW49979 - Compatibility support for GRS wildcard

capability packaged in z/OS V1R2– Extends support back to O/390 V2R8– Also includes performance enhancements and fixes to GRS

wildcard support in z/OS V1R2– Performance problems in ISGNQXIT exit, up to 20% CPU

increase

• OW52896 - Additional performance enhancements– More improvements to ENQ/DEQ with SCOPE=STEP

• OW56809 fixes S738 abend caused by OW52896• II13047 - Fixes to address a hole closed by OW49779• References

– IBM Technical Support Search, use APAR # as keyword– Cheryl Watson’s Hot Flashes #8, p. 11, at

http://www.share.org/proceedings/sh99/SHARE/data/S2543.pdf


RACF, USS UID/GID SEARCH• If sharing RACF DB with pre-OS/390 V2R10 systems,

use UNIXMAP class + IRRUMAP, IRRGMAP VLF classes– Avoids sequential search of RACF DB for UID or GID

associations

• If all systems are OS/390 V2R10 or higher, conversion to Application Identity Mapping stage 3……– Can improve performance even more– Can eliminate need for UNIXMAP, IRRUMAP, IRRGMAP– IRRIRA00 conversion utility is used to migrate to AIM stage 3

• References– z/OS Release 3 and 4 Implementation, page 180, at http://www.

redbooks.ibm.com/redbooks/pdfs/sg246581.pdf

– Optimizing RACF Performance, Walt Farrell, p. 7, at http://www.ibm.com/servers/eserver/zseries/zos/racf/pdf/r00_tuning_racf.pdf

– z/OS 1.4 User Experience at Boeing Company, Deborah Carnes, p. 25, at http://docs.share.org/proceedings/sh100/s2868b.pdf


MVS LOGGER• PQ48163 - Delays on Logger Writes using CF

Logstreams– CICS EC WRITE JOURNAL WAIT causes task LG_DEFER suspend– Log Defer Interval (LGDFINT) in SIT defines how long to delay

before forcing a Logger write (default is 5 ms.), with the objective of batching Logger writes

– In low volume systems, if log defer crosses into a partition exit, task response time is increased up to region exit interval (ICV, default=1 sec.)

– Circumvention is LGDFINT=0 (default OK for DASD logging)– PQ48163 does not provide a fix (fixed in a future release)

• PQ57850 - A fix for CICS TS V1.3• References

– IBM Technical Support Search, use APAR # as keyword– z/OS & OS/390 Performance Hot Topics, Kathy Walsh, p. 15, at

ftp://ftp.software.ibm.com/software/mktsupport/techdocs/hot02.pdf


OSA EXPRESS WITH QDIO• PQ53480 - High CPU consumption when using

Gigabit Ethernets– VTAM cannot keep up with incoming data from OSA Express

as it delivers it to TCP/IP– After delivering data to TCP/IP, VTAM checks for more. If so,

another Programmed Controlled Interrupt (PCI) is simulated to read more data, & so on until all data is delivered

• OSA Express communicates directly with S/390 memory via data queues, hence the PCI simulation

– When VTAM cannot keep up with data, PCI simulation runs constantly, using high amounts of CPU

– PQ53480 changes VTAM to count # of PCI simulations it runs & reschedule/exit after unstated amount of simulations

• References– IBM Technical Support Search, use PQ53480 as keyword


LEGALITIES

• Performance impact of an item is dependent on your configuration, applications, volume, capacity, and environment; carefully research any item that appears to be relevant. All information is distributed on an “as is” basis, with no form of warranty either expressed or implied.

• IBM trademarks - CICS, CICS TS, CP, CSM, DFSMS, DFSMSdss, ESTOR, FICON, GRS, Hiperspace, IBM, IMS, JES2, LPAR, MVS, OSA Express, OS/390, QDIO, PDSE, RACF, SMS, System Resource Manager, SRM, S/390, TCP/IP, UNIX System Services, VSAM, VTAM, WLM, z/Architecture, z/OS, zSeries, z/800, z/900

• Computer Associates trademark - SAR• Mantissa Corporation trademark - QSERV


QUESTIONS AND ANSWERS

• Ask your questions now– Mark Brunelli will explain

• Ask your questions later– Ask the Expert on Search390.com, at http://search390.

techtarget.com/ateQuestion/0,289624,sid10_cid475121_tax292523,00.html

• Questions I can’t answer now will be, on Search390.com

• Email - [email protected]• Website - http://www.mainframehelp.com• Migration Starter Kits - http://www.mainframehelp

.com/upgrade_plan_templates.htm


QUESTIONS

AND

ANSWERS

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