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Case Study: Data Management

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In this case study, we will explore how JCL (Job Control Language) can be used to manage data effectively in a mainframe environment. We will cover the following key aspects:

  1. Introduction to Data Management in JCL
  2. Setting Up the Environment
  3. Creating and Managing Data Sets
  4. Data Backup and Recovery
  5. Data Archiving
  6. Practical Exercises

  1. Introduction to Data Management in JCL

Data management is a critical aspect of mainframe operations. JCL provides robust mechanisms to define, manipulate, and manage data sets. This case study will demonstrate how to:

  • Define and allocate data sets.
  • Perform data backup and recovery.
  • Archive data for long-term storage.

  1. Setting Up the Environment

Before we dive into the practical examples, let's set up the environment. Ensure you have access to a mainframe system with the necessary permissions to create and manage data sets.

Example JCL Job to Set Up Environment

//SETUP    JOB (ACCT),'SETUP ENV',CLASS=A,MSGCLASS=X,MSGLEVEL=(1,1)
//STEP1    EXEC PGM=IEFBR14
//MYDATA   DD  DSN=MY.DATA.SET,DISP=(NEW,CATLG,DELETE),
//             SPACE=(CYL,(5,5),RLSE),UNIT=SYSDA,
//             DCB=(RECFM=FB,LRECL=80,BLKSIZE=800)

Explanation:

  • JOB Statement: Defines the job with accounting information and message classes.
  • EXEC Statement: Executes the IEFBR14 program, a utility that does nothing but is used to allocate or delete data sets.
  • DD Statement: Defines a new data set MY.DATA.SET with specific attributes.

  1. Creating and Managing Data Sets

Defining Data Sets

Data sets are fundamental storage units in mainframe systems. They can be sequential, partitioned, or VSAM (Virtual Storage Access Method).

Example: Creating a Sequential Data Set

//CREATE   JOB (ACCT),'CREATE DATASET',CLASS=A,MSGCLASS=X,MSGLEVEL=(1,1)
//STEP1    EXEC PGM=IEFBR14
//SEQDATA  DD  DSN=MY.SEQ.DATA,DISP=(NEW,CATLG,DELETE),
//             SPACE=(TRK,(10,5),RLSE),UNIT=SYSDA,
//             DCB=(RECFM=FB,LRECL=80,BLKSIZE=800)

Explanation:

  • DSN: Specifies the data set name.
  • DISP: Defines the disposition of the data set (NEW, CATLG, DELETE).
  • SPACE: Allocates space in tracks.
  • DCB: Defines the data control block attributes.

Managing Data Sets

You can perform various operations on data sets, such as copying, deleting, and renaming.

Example: Copying a Data Set

//COPY     JOB (ACCT),'COPY DATASET',CLASS=A,MSGCLASS=X,MSGLEVEL=(1,1)
//STEP1    EXEC PGM=IEBGENER
//SYSPRINT DD  SYSOUT=*
//SYSIN    DD  DUMMY
//SYSUT1   DD  DSN=MY.SEQ.DATA,DISP=SHR
//SYSUT2   DD  DSN=MY.SEQ.DATA.COPY,DISP=(NEW,CATLG,DELETE),
//             SPACE=(TRK,(10,5),RLSE),UNIT=SYSDA,
//             DCB=(RECFM=FB,LRECL=80,BLKSIZE=800)

Explanation:

  • PGM=IEBGENER: Uses the IEBGENER utility to copy data.
  • SYSUT1: Input data set.
  • SYSUT2: Output data set.

  1. Data Backup and Recovery

Data Backup

Regular backups are essential to prevent data loss. Use the ADRDSSU utility for data set backup.

Example: Backing Up a Data Set

//BACKUP   JOB (ACCT),'BACKUP DATASET',CLASS=A,MSGCLASS=X,MSGLEVEL=(1,1)
//STEP1    EXEC PGM=ADRDSSU
//SYSPRINT DD  SYSOUT=*
//DUMP     DD  DSN=MY.SEQ.DATA.BACKUP,DISP=(NEW,CATLG,DELETE),
//             UNIT=SYSDA,SPACE=(CYL,(5,5),RLSE)
//SYSIN    DD  *
  DUMP DATASET(INCLUDE(MY.SEQ.DATA)) -
       OUTDD(DUMP)
/*

Explanation:

  • PGM=ADRDSSU: Uses the ADRDSSU utility for backup.
  • DUMP: Specifies the backup data set.
  • SYSIN: Contains the control statements for the utility.

Data Recovery

To recover data, use the same ADRDSSU utility.

Example: Recovering a Data Set

//RECOVER  JOB (ACCT),'RECOVER DATASET',CLASS=A,MSGCLASS=X,MSGLEVEL=(1,1)
//STEP1    EXEC PGM=ADRDSSU
//SYSPRINT DD  SYSOUT=*
//RESTORE  DD  DSN=MY.SEQ.DATA,DISP=(NEW,CATLG,DELETE),
//             UNIT=SYSDA,SPACE=(CYL,(5,5),RLSE)
//SYSIN    DD  *
  RESTORE DATASET(INCLUDE(MY.SEQ.DATA)) -
          INDD(DUMP)
/*

Explanation:

  • RESTORE: Specifies the data set to be restored.
  • INDD: Input data set for the restore operation.

  1. Data Archiving

Archiving data helps in managing storage efficiently by moving less frequently accessed data to long-term storage.

Example: Archiving a Data Set

//ARCHIVE  JOB (ACCT),'ARCHIVE DATASET',CLASS=A,MSGCLASS=X,MSGLEVEL=(1,1)
//STEP1    EXEC PGM=IEBGENER
//SYSPRINT DD  SYSOUT=*
//SYSIN    DD  DUMMY
//SYSUT1   DD  DSN=MY.SEQ.DATA,DISP=SHR
//SYSUT2   DD  DSN=ARCHIVE.MY.SEQ.DATA,DISP=(NEW,CATLG,DELETE),
//             UNIT=TAPE,SPACE=(CYL,(5,5),RLSE),
//             DCB=(RECFM=FB,LRECL=80,BLKSIZE=800)

Explanation:

  • UNIT=TAPE: Specifies that the data set is to be archived to tape storage.

  1. Practical Exercises

Exercise 1: Create and Copy a Data Set

  1. Create a sequential data set named STUDENT.DATA.
  2. Copy STUDENT.DATA to STUDENT.DATA.COPY.

Solution

//EXER1    JOB (ACCT),'CREATE AND COPY',CLASS=A,MSGCLASS=X,MSGLEVEL=(1,1)
//STEP1    EXEC PGM=IEFBR14
//STUDDATA DD  DSN=STUDENT.DATA,DISP=(NEW,CATLG,DELETE),
//             SPACE=(TRK,(10,5),RLSE),UNIT=SYSDA,
//             DCB=(RECFM=FB,LRECL=80,BLKSIZE=800)
//STEP2    EXEC PGM=IEBGENER
//SYSPRINT DD  SYSOUT=*
//SYSIN    DD  DUMMY
//SYSUT1   DD  DSN=STUDENT.DATA,DISP=SHR
//SYSUT2   DD  DSN=STUDENT.DATA.COPY,DISP=(NEW,CATLG,DELETE),
//             SPACE=(TRK,(10,5),RLSE),UNIT=SYSDA,
//             DCB=(RECFM=FB,LRECL=80,BLKSIZE=800)

Exercise 2: Backup and Recover a Data Set

  1. Backup STUDENT.DATA to STUDENT.DATA.BACKUP.
  2. Recover STUDENT.DATA from STUDENT.DATA.BACKUP.

Solution

//EXER2    JOB (ACCT),'BACKUP AND RECOVER',CLASS=A,MSGCLASS=X,MSGLEVEL=(1,1)
//STEP1    EXEC PGM=ADRDSSU
//SYSPRINT DD  SYSOUT=*
//DUMP     DD  DSN=STUDENT.DATA.BACKUP,DISP=(NEW,CATLG,DELETE),
//             UNIT=SYSDA,SPACE=(CYL,(5,5),RLSE)
//SYSIN    DD  *
  DUMP DATASET(INCLUDE(STUDENT.DATA)) -
       OUTDD(DUMP)
/*
//STEP2    EXEC PGM=ADRDSSU
//SYSPRINT DD  SYSOUT=*
//RESTORE  DD  DSN=STUDENT.DATA,DISP=(NEW,CATLG,DELETE),
//             UNIT=SYSDA,SPACE=(CYL,(5,5),RLSE)
//SYSIN    DD  *
  RESTORE DATASET(INCLUDE(STUDENT.DATA)) -
          INDD(DUMP)
/*

Conclusion

In this case study, we have covered the essential aspects of data management using JCL, including creating, managing, backing up, recovering, and archiving data sets. By following the examples and exercises, you should now have a solid understanding of how to handle data management tasks in a mainframe environment using JCL. This knowledge is crucial for maintaining data integrity and ensuring efficient data operations in your mainframe systems.

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