VSAM Cardinal

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  • VSAM Cardinal

  • VSAM Cardinal Abstract This presentation addresses issues relevant to all z/OS enterprises that exploit VSAM. When the issues addressed by this presentation are ignored, unintentionally overlooked, or put on the back burner for higher priority tasks, both application- and system-level performance will suffer. The intent is to provide you with a systematic and automated approach to creating and maintaining high levels of integrity, productivity, and performance in your VSAM environment.

  • VSAM Cardinal Abstract, cont.

    We will discuss how VSAM natively controls sharing of datasets and the impact on application performance, availability, and integrity of the underlying data. We will also address the challenges associated with establishing and maintaining a high-performance VSAM environment without having a negative impact on the productivity of the IT staff.

  • VSAM Sharing and Integrity Challenge

    VSAM allows only one program to update a dataset (with full integrity) Can cause long batch cycles Reduces the availability of online systems

    Manipulation of the SHAREOPTIONS parameter Further reduces online availability Negative impact on application performance

  • VSAM Sharing and Integrity Band-Aids

    Re-develop applications using a proprietary DBMS

    Develop CICS transactions that perform batch functions

    Create shadow databases Make batch programs open and close files Homegrown software for remote file access

    (function shipping?)

  • VSAM Sharing and Integrity Band-Aids

    Manipulation of the SHAREOPTIONS parameter Further reduces online availability Negative impact on application performance Four specific options with various levels of access and integrity

  • VSAM Sharing and Integrity SHAREOPTION 1

    Any number of OPENs for batch or online These OPENs must be read-only Only one program (or transaction) can open

    for UPDATE (write) Provides complete integrity

  • VSAM Sharing and Integrity SHAREOPTION 2

    Any number of OPENs for batch or online These OPENs must be read only Only one program (or transaction) can open

    for UPDATE (write) VSAM locks the CI, but users will have to

    ENQ on the record key for integrity

  • VSAM Sharing and Integrity SHAREOPTION 3

    Completely shareable by anybody and everybody

    Integrity? SHAREOPTION 3 applies to both cross-

    region and cross-system integrity

  • VSAM Sharing and Integrity SHAREOPTION 4

    Completely shareable by everybody (READ and UPDATE)

    SHAREOPTION 3 level integrity, use ENQ/DEQ for each I/O operation

    SHAREOPTION 4 applies to both cross- region and cross-system integrity

  • VSAM Sharing and Integrity Band-Aids

    Locking RLS could be used

    Enables CICS to do all writes This might allow for reads Read integrity is not guaranteed

    So again, user, do your own ENQs

  • VSAM Sharing and Integrity The optimal approach

    Control VSAM sharing with a transparent Intelligent File Management System (IFMS) Intercepts, controls, and executes batch and online I/O requests Could run in its own address space Functions as the VSAM traffic cop with full data integrity

    Not limited by number of read/update users

  • IFMS in the Environment CICS



  • IFMS in the Environment Capitalizes on CICSs multi-programming capabilities

    Transparently intercepts VSAM requests for files and performs I/O operations with integrity (batch and online)

    Two methods of communication LU 6.2 for remote file access XMS if both the batch job and CICS are

    running on the same CPU

  • IFMS Environment


    Application Program

    with IFMS Intercept

    IFMS I/O

    Manager and Online Interfaces

    VTAM LU6.2


    MVS Cross Memory Services

  • IFMS in the Environment Complete data integrity

    I/O is centralized within CICS Both CICS and batch jobs can update the

    same file simultaneously Total transparency

    No programming changes No new interfaces to learn

    Selective SYNCpointing and Recovery (SSAR)

  • IFMS in the Environment Control and flexibility

    You define which jobs are impacted You determine max number of jobs that may

    simultaneously access CICS

    Works within your security environment Dynamically suspend, restart, cancel, or

    change the number of I/Os being sent to CICS by a given job

  • Primary Menu Screen

  • Selected Dataset Screen

  • Job Maintenance Screen

  • Job History Screen

  • Selected DDNAME Screen

  • Selected DDNAME Screen

  • IFMS in the Environment Selective SYNCpointing and Recovery (SSAR) Tier 1 Tier 2 Tier 3

  • IFMS with SSAR Needless to say, Tier 1 is the simplest to implement and is mostly suited for short-running jobs that do few updates. Tier 1 relies on CICS DTB for recovery.Tier 2 is straight forward, as well, but will need a basic understanding of journaling. Tier 3 will need some attention

  • IFMS with SSAR The SYNC level field on the JOB MAINTENANCE screen identifies journaling (Tier 2) and is the number of CICS file ENQUEUEs allowed before a SYNCpoint is issued

  • IFMS with SSAR With Tier 1 or 3, 0 (zero) is used With Tier 2, CICS does not journal

    Journaling is from within the IFMS Journaling is completely transparent to the application

  • IFMS with SSAR Recovery (in Tier 2) is started using the journal


    VSAM Files

    Program A IFMS

    Program B IFMS


    A Files

    B Files


  • IFMS with SSAR Unlike the prior two options, Tier 3 will require program modifications

    Tier 3 is best suited for long-running jobs

  • IFMS Solution Summary Unlimited sharing with integrity

    Total transparency No source code modifications

    No recompiling of current code No mods to existing system software No proprietary address spaces to support Support for all programming languages No new interfaces or commands to learn Easy installation, activation/deactivation

  • What about VSAM Performance? VSAM is the most widely used access method in one form or another Dwindling amount of mainframe tuning expertise When properly tunedvery strong performer Without proper tuning

    Online and batch performance suffers Can lead to unnecessary processor and DASD

    upgrades Lost productivity performing file reorgs

  • What about VSAM Performance? Improving VSAM performance

    Identify obvious waste and inefficiencies Run a FREECYLINDERS report Run an EMPTY report Run a Not Updated Since 20xx report

    Analyzing the remaining legitimate datasets Get professional help!

    Find a software solution that streamlines the process of analyzing and managing VSAM

    Design and allocate Analyze Reporting

  • MENU

  • Dataset Design

  • Dataset Design Profile

  • Search and List Capabilities

  • Background/Foreground Analysis

  • Batch Analysis

  • Foreground Analysis

  • Profile Update Menu

  • Analysis Reporting Options

  • Background Job Profile

  • Extended List Catalog

  • Dataset Recommendations Profile

  • VSAM Performance Summary

    VSAM tuning is critical Limited human resources are available

    A good software solution will support the major components of your VSAM environment Design/Allocate Analysis Recommendations

  • VSAM Performance Summary Reporting Reduce/eliminate unnecessary reorgs

    Reduced operational costs for DASD Model and design VSAM files based on current or modified definitions

    ISPF interface for quick ad hoc changes