Front cover VSAM Demystified - IBM Redbooks

1 CoverVSAM DemystifiedMary LovelaceJose DovidauskasAlvaro SallaValeria SokalLearn the latest vsam functions and manage vsam dataUnderstand, evaluate, and use vsam properlyLearn problem determination and recommendationsInternational Technical Support OrganizationVSAM DemystifiedMarch 2013SG24-6105-02 Copyright International Business Machines Corporation 2001, 2012, 2013. All rights to Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP ScheduleContract with IBM Edition (March 2013)This edition applies to z/OS Version 1 Release 13 DFSMS (product number 5694-A01).

2 Note: Before using this information and the product it supports, read the information in Notices on page xi. Copyright IBM Corp. 2001, 2012, 2013. All rights .. xiTrademarks .. xiiPreface .. xiiiThe team who wrote this book .. xiiiNow you can become a published author, too! .. xivComments welcome.. xivStay connected to IBM Redbooks .. xivSummary of changes.. xviiMarch 2013, Third Edition .. xviiChapter 1. vsam basics.. vsam functions by release level.. What is vsam ? .. What is an access method? .. vsam access types.

3 vsam functions.. Catalog management .. Record management .. vsam terminology and concepts .. Logical record .. Physical record .. Control interval .. Spanned records.. Control area .. Components .. Clusters .. Alternate indexes .. Sphere .. Splits .. vsam buffering .. String multiprocessing.. Catalog Search Interface .. Extended Address Volume .. vsam data set organizations .. Key-sequenced data set (KSDS) .. Entry-sequenced data set .. Relative record data set.

4 Variable relative record data set .. Linear data set .. Comparing vsam data set organizations .. Selecting a vsam data set type .. Data striping .. Processing a vsam data set .. Defining vsam data sets .. Allocating a vsam data set .. Opening a vsam data set .. Accessing vsam data set.. 39iv vsam Unallocation .. vsam exploiters .. DB2 .. zSeries file system .. Hierarchical file system .. CICS .. DFSMShsm.. DFSMSrmm .. Java Record I/O (JRIO).. 42 Chapter 2.

5 Managing your vsam data sets .. Reorganization considerations .. Reorganizing because of lots of CI/CA splits .. Reorganizing because of loss of useful space in data CA .. DB2 table space reorganization .. Sharing vsam data sets .. Integrity .. Sharing vsam data sets .. Write and read integrity .. vsam sharing mechanisms .. Sharing data in a single vsam control block structure .. Sharing data with many vsam control block structures .. General share options considerations.. Protecting vsam data set through DISP parameter.

6 Extended format .. Extended format characteristics .. Creating an extended format data set.. Extended addressability (EA) .. Catalog Search Interface .. CSI highlights .. DITTO/ESA .. Major sources of vsam processing options .. Access method Control Block (ACB) .. DD statement keywords .. Catalog BCS and VVDS entries .. SMS constructs .. Media Manager, Open, Close, EOV in vsam .. vsam and 64 bits in real storage .. Special considerations for COBOL users and SMB .. Positioning error.

7 Waits and hangs .. ISAM data set programs .. 79 Chapter 3. Guidelines for ICF catalog and vsam .. ICF catalog basics.. Basic catalog structure (BCS) .. vsam volume data set (VVDS) .. Factors affecting catalog performance .. Catalog configuration .. BCS definition .. VVDS definition .. Caching catalogs .. GRS configuration.. 93 Contents Catalog problem determination .. Using the EXAMINE command .. Using DIAGNOSE command .. Locking Catalogs .. Catalog management .. Catalog sharing.

8 Creating a balanced catalog environment.. Reorganizing catalogs .. Using the Catalog Search Interface (CSI).. SYSZTIOT catalog contention detection.. Catalog autotuning function .. Catalog backup and recovery .. BCS forward recovery .. RACF and REPRO MERGECAT command .. Catalog IMBED/REPLICATE health check .. Helpful frequently asked questions .. Diagnosing prolonged catalog ENQ times .. Monitoring the catalog address space .. 124 Chapter 4. vsam performance.. Performance analysis.

9 Service level agreement (SLA) .. Transaction response time components .. External throughput rate .. I/O performance .. vsam performance management .. vsam defaults and rule-of-thumbs .. Parameters affecting performance .. Allocation units .. Optimizing control area (CA) size .. Partial release .. Allocation constraint relief .. Control interval size .. FREESPACE definition for KSDS and VRRDS .. Data Control Area Reclaim .. Index options.. Keyrange and ordered options .. Share options.

10 Initial load option .. Region size .. Buffering options .. How BUFFERSPACE, BUFSP, BUFND, and BUFNI affect buffering .. Buffering techniques .. Data compression .. vsam data striping .. vsam performance by scenarios .. I/O response time components .. Performance scenario that uses RMF reports .. Reducing the number of I/Os .. Decreasing the vsam I/O response time .. Decreasing vsam CPU time .. MIDAW facility.. Performance monitors .. 206vi vsam Resource measurement facility.