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May 2008 John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International www.csi-international.com [email protected]

May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International [email protected]

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Page 1: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

VSE/VSAM – Under the covers

John MycroftProduct Development Manager

CSI Internationalwww.csi-international.com

[email protected]

Page 2: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Acknowledgement

With grateful thanks to Dan Janda, The Swami of VSAM, from whom much of this presentation was stolenTo CSI for providing me with Data-Miner, CSI-Sort and a machine to create the examplesTo my fellow developers at CSI who put up with my hogging the machine for hours on end

Page 3: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Abstract

Overview of VSAM & its components. We take a look at what a VSAM file really looks like and how to soup up its performance.We also look at some common mistakes and how to avoid them.This presentation and its materials are copyrighted and developed by John Mycroft from a presentation originally copyrighted by Dan Janda. Permission is granted for WAVV to reproduce this presentation for distribution to its members at no charge.Trademarks:

IBM, VSE, VSE/ESA, zVSE, CICS & DL/I are trademarks or registered trademarks of the IBM CorporationThe Swami of VSAM is a trademark of Dan Janda.

Page 4: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

VSE/VSAM Overview

Virtual Storage Access MethodFor disk files

Sequential – “Entry Sequence Dataset” or ESDSBegin at the beginning, go on til you get to the end and then stop

Indexed – “Keyed Sequence Dataset” or KSDSProcess by key or sequentially or a mixture

Direct – “Relative Record Dataset” or RRDS (fixed) or VRDS (variable)

Calculate a record’s location in the file to access itAlternate index (AIX) – gives an alternative route to a KSDS

Allows unique & non-unique keys

Page 5: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

VSE/VSAM Functional areas

CatalogVolume & file informationUsage statistics

Disk space managementSpace allocation including secondary allocationsVSAM and VSAM/SAM filesSystem filesLibraries

Page 6: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

VSE/VSAM Functional areas

IntegrityPerformance

Data transfer sizeBufferingBackup / restoreFile sharing between jobs and systems

Page 7: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Processing a VSAM fileSequentially (ESDS)

Forward or backward

Keyed access (KSDS)Direct by full or partial (generic) keySequentially, forward or backwardSkip sequential, forward or backward

Addressed access (RRDS, VRDS)Direct, by record addressSequential & skip sequential

Alternate Index AccessSame as keyed accessAlso direct access by non-unique key

Page 8: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

How VSAM stores data

We’re going to look at How VSAM stores records logically on disk

Performance considerations

How VSAM physically stores data on diskDisk space usage calculationsOptimizing disk capacityPerformance considerations

VSAM jargonControl IntervalControl AreaCI & CA splitsFreespaceRDF, CIDF

Page 9: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

VSAM Jargon

Control Interval (CI)“Smallest unit of data transfer between main & disk storage”

In other words, when you read a record, VSAM reads the whole CI that contains that recordThink of it as the same as a block of records in a sequential file if you like (though it’s laid out differently)

A CI can initially contain 1 or more recordsMore can be insertedSome or all can be deletedWhen you try to add a new record to a CI with no room, a “CI split” takes place – more about that later

Page 10: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Layout of a control interval

ALL VSAM FILES ARE VARIABLE LENGTHEven if all the records are the same sizeRec 1 – Rec n 1 to n logical records of any lengthFreespace Unused space in CI for inserting records or making existing records longerRDFs 3 byte record descriptor field

ESDS/KSDS 1 per LRECL, 1 for all consecutive records of same lengthRRDS one per numbered record slot

CIDF 4 byte Control Interval Descriptor Field

Rec 1 Rec 2 Rec 3 Rec … Freespace RDFs CIDF

Page 11: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Control Area (CA)

CA size is the smallest of :One cylinder orThe size of the primary allocationThe size of the secondary allocation

The number of CIs per CA depends on the device and the CI and CA sizesIt is generally a good idea to go for the biggest CA possible

A CA is a group of CIs. In a KSDS, all the data CIs in a CA are indexed by one index CI

CI 0 CI 1 CI 2 CI 3 CI 4 CI 5 CI 6 CI 7 CI 8 CI 9

CI10 CI11 CI12 CI13 CI14 CI15 CI16 CI17 CI18 CI19

CI20 CI21 CI22 CI23 CI24 CI25 CI26 CI27 CI28 CI29

Page 12: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Index Control Interval (Index CI)

CI 0 CI 1 CI 2 CI 3 CI 4 CI 5 CI 6 CI 7 CI 8 CI 9

CI10 CI11 CI12 CI13 CI14 CI15 CI16 CI17 CI18 CI19

CI20 CI21 CI22 CI23 CI24 CI25 CI26 CI27 CI28 CI29

A CI in an index containing pointers to The next level in the index orThe Data CI in the CA – this is referred

to as a Sequence Set CI

Index CI

Page 13: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Index and data structure

Balanced treeSparse index

Always just 1 high-level index CIThere can be 0 to many intermediate level index CIsThere can be one or more low-level (sequence set) index CIs.If there is only 1 sequence set CI, it is also the high-level index CI

Page 14: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

And now the bit you’ve all been waiting for……

Page 15: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Performance rules of thumb

Use largest data CI possible, especially for sequential workUse as small an index CI as you can (but not too small!)Use large data CA – allocate primary and secondary as at least 1 cylinderAvoid too many extents / allocations

Page 16: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Allocation calculations

CI freespace = CI Size * Freespace %

Number of records per CI“Fixed” length:

(CI Size -10 –Freespace) / LRECL

Variable length:(CI Size -7 –Freespace) / (Average LRECL +3)

Page 17: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

What’s in a CI?

Data and control info (end of CI)

Page 18: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

CI control information

At the end of each data CI

Page 19: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Data records

Page 20: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

The CIDF

Note – (back 2 slides) free space has data in it from earlier CI split

Page 21: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

The Index

Page 22: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Allocation calculations

Calculate Freespace in each CAGet number of CIs per CA from LISTCAT or device characteristics (3390, 12 x 4K CIs/track, 180/cyl)CA freespace = No of CIs per CA * CA Freespace %, rounded upNumber of CIs loaded per CA =

CIs per CA – CA freespace

Number of records loaded per CA = Loaded CIs in CA * No of recs in CI

Page 23: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

VSAM Catalogs

Exactly one master catalogAssigned at IPL with DEF CAT orDEFINE MCAT IDCAMS command

User catalogs – 0 to manyNo more than 1 per volumeCatalog can own multiple spaces on a volumeMany catalogs can own space on a volume

Page 24: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

VSAM Catalogs

Catalog contains :-Self-describing recordsUser catalog pointersVolume definitionsSpace definitionsCluster (file) definitionsComponent (data, index) definitionsAIX & Path definitions

Page 25: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Catalog recommendations

Use naming conventionsName Cluster, Data and Index components explicitlyUse partition / system independent names where applicable

SeparateFiles seldom defined or deletedFiles often defined or deletedOnline critical filesBatch files

Multiple baskets – all the eggs won’t get broken

Page 26: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

More recommendations

Don’t use recoverable catalogsHangover from 2314 / 3330

Backup is vastly betterIDCAMS, Faver, Maxback, Dr D, user-written …

Page 27: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

CI & CA splits and freespace

You try to insert a record in a CI or extend a record already thereIf there is enough free space in the CI, everyone moves up, record is inserted and CI rewrittenBUT what if there isn’t enough free space????

Page 28: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

CI & CA splits

CI split – 4 physical IOsSet “Split in progress”, write CIMove half of records to new CI & write itUpdate sequence set, write index CIErase moved records from old CI, turn off “Split in progress”, write old CI

BUT…..

Page 29: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Failure in CI split

System failureCorrected next time CI is updated

No free CI in the CACA split is needed

Remember – 1 physical IO = 30,000 – 40,000 CPU instructions…

Page 30: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

CA Split

MANY physical reads and writesSet “Split in progress”, write sequence set CIMaybe get new extentFormat new CA at HURBA positionRead / write half of CIs to new CAWrite new sequence set CI for new CAUpdate higher level index CIsErase moved CIs from old CA, write empty CIsWrite updated original sequence set CI

Page 31: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Recommendations

Don’t worry about CI splitsAvoid excessive CA splits by defining CA freespaceDon’t do a reorg just because you have done n CI / CA splits

Page 32: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

To reorg or not to reorg?

“We’ve done 1000 CA splits – better reorg!”Inserts tend to be clusteredCI / CA split creates freespace where it is needed, allows faster insertsReorg gets rid of freespace, causing more CI / CA splits

Page 33: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

My house

Buy a 3 bedroom houseHave 2 kidsMa-in-law moves in – add a roomMa-in-law moves out – demolish room Have another kid - Add a bedroomOldest kid goes to college – demolish bedroomOldest kid brings home girlfriend……

Page 34: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

My KSDS

Get some spaceInsert records causing CI splitsREORG!!Delete some records, freeing spaceREORG!!!Add records, causing CA splitsREORG!!!!

Page 35: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Recommendations

Avoid frequent reorgsOnce a split has occurred, the processing cost has been paidDon’t reorg to compress out free space

Page 36: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Reorgs

Understand your application1 “hot spot”

Little distributed freespace – let it splitMany hot spots

Little distributed freespace – let it splitEven distribution – no hot spots

Use distributed freespace

Page 37: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Freespace

•3% of each CI is empty

•5% of CIs in each CA are empty

•3% of 2048 = 61 bytes = 0 records (or, at most, 1)

•5% of 315 CIs per CA = 16 CIs

Page 38: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Freespace

3% CI freespace where CISZ=2048 and average LRECL=120

No room in this CI for an average length record

Page 39: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Altering freespace

Initial freespace set via DEFINE eg 10% of CI and 5% of CAIf inserts are clustered, consider

DEFINE with 0% freespace, thenLoad the “fixed” part of the file then ALTER freespace to non-zeroLoad the “variable” part of the file

Page 40: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Freespace ain’t free space

Freespace is empty, not usedYou still have to pay IBM for it

Page 41: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Strings

VSAM allows multiple concurrent processing e.g.

CICS transactionsBrowsingUpdatingPlaceholders (“strings”) hold file location info

Page 42: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Shared / non-shared resources

Non-shared resources (NSR)Each string has its own buffersMultiple copies of a CI may be in memoryWorks well for batch

Local Shared Resources (LSR)Many strings share a pool of buffersOnly 1 copy of a CI in the poolIdeal for online

Page 43: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Recommendations - NSR

Non-shared resourcesEach string must have enough index buffers

Bad – 1 buffer (old default)OK – 1 buffer per index level (new default)Good – enough buffers for all high level indexes + 1 moreBest – enough buffers to hold entire index

Page 44: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Recommendations - LSR

Local Shared Resource buffersSame index buffer needs as NSR (buffers are per pool, not per string)Monitor VSAM LSR stats to make sure BUFNI keeps up with index growthMonitor data buffers for high hit rates

Page 45: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

IO with NSR

VSAM uses chained IO to read ahead and write behind

Better to read many CIs in one IO Block big

Large CI sizesBe aware that VSAM will split CIs into smaller blocks to save space

Eg 3390 with 32K CI gets written as 2 x 16K blocks giving 1.5 CIs = 48K/track

Buffer big½ to 1 cyl of BUFND to minimize IO

Page 46: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

IO with LSR

VSAM reads 1 CI at a time, even for sequential processing

Page 47: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Monitor your stats

LISTCAT before and after critical jobData & Index EXCPs – the fewer the better. Index EXCPs should be close to number of index CIs.Job Accounting data

IO count by deviceOveral CPU & IO activity

CICS statsShows logical / physical IO counts by fileLSR pool hits and misses

VSAM buffer stats – in VSE/ESA examples docLSR is in 31 bit – use LOTS but don’t page

Page 48: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Sharing VSAM datasets

VSAM can share files among partitionsAnd among VSE systems

BUTTANSTAAFL (Robert Heinlein)Sharing is not a performance option (Dan Janda)It’s your gun and your foot (Steve Huggins)

Page 49: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Sharing VSAM datasets

Sharing is based onThe type of sharing you ask for (SHAREOPTIONS)VSE Lock Table within a single VSE systemVSE Lock File when sharing across VSE systems

VSE sharing mechanism is not compatible with zOS or zVM

Page 50: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Sharing VSAM datasets

Sharing at OPEN / CLOSE timeEntries checked and placed in / removed from lock tableIf DASD volume is added as shared (ADD cuu,SHR), it is added to lock file

VSE & VSAM allow concurrent processing to protect against concurrent updates messing up the file

Page 51: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Sharing VSAM datasets

Integrity classes – your choiceNO INTEGRITY – VSE & VSAM provide no data protection: it’s all up to you. Your data can be messed up.WRITE INTEGRITY – VSE & VSAM protect against concurrent updatesREAD INTEGRITY – VSE & VSAM make sure your programs always see the latest version of a record

The priceHigher levels & broader scopes of integrity lead to more CPU and IO activity

Page 52: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

SHAREOPTIONS

Ready – Fire – AimSet in DEFINE CLUSTERGet it wrong & be prepared to sufferIf a disk drive isn’t shared between VSEs, don’t ADD it with SHR as this causes lock file IO

Page 53: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

SHAREOPTIONS & Locking

SHR(1) 1 output OR many input External lock at OPEN, unlock at CLOSE

SHR(2) 1 output AND many inputExternal lock at OPEN, unlock at CLOSE

SHR(3) No checking or locking Prepare for garbage data

SHR(4) Many output in one VSE & many input OPENs across all VSEs

External lock at OPEN, unlock at CLOSEExternal lock at access, unlock at release

SHR(4 4) Many output OPENs across all VSEs + many input OPENs

Locks same as SHR(4)

Page 54: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Alternate indexes (AIX)

An AIX is a VSAM KSDS, acting as a “pointer file” for another file

Target file (“Base Cluster”) can beKSDS – pointers are KSDS key valuesESDS – pointers are Relative Byte Addrs

Great for multiple or non-unique keysBUT

Processing via an AIX needs IO to both the AIX and to the base cluster

Page 55: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Setting up an AIX

DEFINE CLUSTER for base clusterDEFINE AIX for the alternate index

Give base cluster’s name & alternate keyData & Index CI sizes

DEFINE PATHAllows specifying of NOUPGRADE paths

BLDINDEXReads primary & alternate key info from base clusterSorts into alternate key sequenceLoads alternate index

Page 56: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

AIX recommendations

To process the base cluster in AIX order, it is better to sort it and use the SORTOUT fileRemember VSAM processes base clusters directly based on AIX valuesBase cluster will need lots of index buffers for batch processing. Give Base cluster large BUFFERSPACE on DEFINE or ALTER

Page 57: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

AIX and CICS

“SPHERE” – a base cluster and all its AIXs related to itRequirements

Each sphere must be wholly within one LSR poolUse Dataset Name Sharing

In CICS 2.3, add BASE= to FCT entry forBase cluster file entryEach related path file entry

This is automatic in CICS TSSHR(2) is usually bestMake sure your CICS and VSAM service is current!

Page 58: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

•MYTH 1 - RECOVERY is a good option for a dataset

•Oh yeah? RECOVERY makes it possible for you to write a recovery routine to restart loading.

•COPY 50,000 record KSDS-

•SPEED = 6 secs, 1512 I/Os

•RECOVERY = 10 secs, 1925 I/Os

•BUSTED!!!

Page 59: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

•MYTH 2 – No need to sort before loading KSDS

•Load 100,000 record KSDS with Data-Miner COPY

•Elapsed = 7:11,CPU = 51”, EXCP = 294412, CIsplit = 2011, CAsplit = 63

•Sort to KSDS with CSI-Sort

•Elapsed = 0:27,CPU = 6”, EXCP = 4314,

CIsplit = 0 ,CAsplit = 0 BUSTED!!!

Page 60: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

And now the most burning question of the day……

How do you delete an unwanted slide from a Power Point presentation?

Page 61: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

Contacting the presenter

You can contact me by email at [email protected], if you want to find me this evening…

Page 62: May 2008John Mycroft – WAVV 2008 VSE/VSAM – Under the covers John Mycroft Product Development Manager CSI International  johnm@csi-international.com

May 2008 John Mycroft – WAVV 2008

You’ll find me here