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Introduction to the new mainframe © Copyright IBM Corp., 2008. All rights reserved. Chapter 9: Batch processing and the Job Entry Subsystem (JES) Batch.

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Presentation on theme: "Introduction to the new mainframe © Copyright IBM Corp., 2008. All rights reserved. Chapter 9: Batch processing and the Job Entry Subsystem (JES) Batch."— Presentation transcript:

1 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Chapter 9: Batch processing and the Job Entry Subsystem (JES) Batch processing and JES

2 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Objectives Be able to: Give an overview of batch processing and how work is initiated and managed in the system. Explain how the job entry subsystem (JES) governs the flow of work through a z/OS system. Workload Manager

3 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Key terms in this chapter batch processing execution initiator job job entry subsystem (JES) output procedure purge queue spool symbolic reference workload manager (WLM)

4 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. What is batch processing? Much of the work running on z/OS consists of programs called batch jobs. Batch processing is used for programs that can be executed: With minimal human interaction At a scheduled time or on an as-needed basis. After a batch job is submitted to the system for execution, there is normally no further human interaction with the job until it is complete.

5 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. //S1 EXEC PGM=MVSPROG1 //S3 EXEC PGM=MVSPROG2 //S2 EXEC PGM=BPXBATCH, //OPENBATC JOB /* // // PARM='pgm cprog a1 a2' MVS batch program OpenMVS batch program MVS batch program End of job Start of job MVS Batch Job Stream CLASS= ? IMPORTANT Parameter

6 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Batch job STEP1 STEP2 STEPn Batch job STEP1 STEP2 STEPn Batch job STEP1 STEP2 STEPn Example of Batch Processing Batch job STEP1 STEP2 STEPn Batch job STEP1 STEP2 STEPn Batch job STEP1 STEP2 STEPn

7 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. What is JES? In the z/OS operating system, JES manages the input and output job queues and data. JES handles the following aspects of batch processing for z/OS: Receives jobs into the operating system Schedules them for processing by z/OS Controls their output processing

8 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. What is JES? (continued) z/OS offers two types: JES2 and JES3 Some important differences, but both JES2 and JES3: Accept and queue jobs submitted for execution Queue jobs for an initiator -- a JES program that requests the next job in the queue Accept output from a job while it is running and queue the output Can print the output, or save it on spool for an output manager to retrieve.

9 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Job Management

10 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Why do we need JES

11 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. JES FUNCTIONS

12 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. BATCH Jobstreams s# = step number s1s2s3S4s5s6s7 s1s2s3s4 s1s2s3s4s5 s1s2s3s4s5 Automated Scheduler

13 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Batch flow (simplified) i.e – 10 initiators = 10 batch jobs can run concurrently.

14 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. JES2 Queuing Mechanisms

15 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. JES2 has many parts …..

16 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Sample JES2 Start Procedure PROC00 – default procedure library to be used for converting the JCL PROCxx - other user catalogue procedures lib associated with JOBCLASS initialization HASPPARM – Dataset containing intialization statements that will be used for JES2 initialization and conrolling all JES functions

17 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. What is spooling? Spooling is a method for queuing and holding data for input or output. JES uses one or more disk data sets for spooling. Input jobs and printed output from many jobs are stored in the single (conceptual) spool data set. (Simultaneous Peripheral Operations OnLine)

18 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. JES2 Spool Dataset -$DSPOOL $HASP893 VOLUME(DMPSP1) STATUS=ACTIVE,PERCENT=29 $HASP893 VOLUME(DMPSP2) STATUS=ACTIVE,PERCENT=61 $HASP PERCENT SPOOL UTILIZATION ******************************* BOTTOM OF DATA ****** SDSF.ULOG Direct Access Devices containing the spool datasets

19 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. What an initiator does To run multiple jobs asynchronously, z/OS uses initiators to: Ensure that jobs do not conflict in data set usage Ensure that single-user devices (tape drives) are allocated correctly Find executable programs requested by jobs Clean up after the job ends and request the next job Preventing two users from accessing the same data at the same time is critical to z/OS and the ability to do this is one of the defining characteristics of the operating system.

20 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Display Filter View Print Options Help _______________________________ __________________________________________ SDSF INITIATOR DISPLAY DEMOMVS LINE 1-17 (24) COMMAND INPUT ===> SCROLL ===> PAGE NP ID Status Classes JobName StepName ProcStep JobID C ASID ASIDX 1 ACTIVE A CAESTART *OMVSEX JOB09317 A E 2 ACTIVE BA APPLY ASNA81 JOB00029 A INACTIVE CBA INACTIVE DCBA INACTIVE DCBA INACTIVE DCBA INACTIVE DCBA INACTIVE DCBA INACTIVE DCBA INACTIVE DCBA ACTIVE I IMSAMSG1 DFSMPR REGION JOB02707 I ACTIVE I IMSBMSG1 REGION JOB02743 I ACTIVE I IMSBIFP1 DFSIVA4 IMS81 JOB02745 I ACTIVE I IMSTMSG1 DFSMPR REGION JOB02799 I INACTIVE T INACTIVE A INACTIVE A F1=HELP F2=SPLIT F3=END F4=RETURN F5=IFIND F6=BOOK F7=UP F8=DOWN F9=SWAP F10=LEFT F11=RIGHT F12=RETRIEVE SDSF.INIT /D $DI /D $SPOOL

21 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. SDSF.ULOG /$D I Display Filter View Print Options Help SDSF ULOG CONSOLE DNET855 LINE 0 COLUMNS COMMAND INPUT ===> SCROLL ===> PAGE ********************************* TOP OF DATA ********************************* ISF031I CONSOLE DNET855 ACTIVATED -$DI $HASP892 INIT(1) $HASP892 INIT(1) STATUS=ACTIVE,CLASS=A,NAME=1, $HASP892 ASID=00E9,JOBID=JOB09317 $HASP892 INIT(2) $HASP892 INIT(2) STATUS=ACTIVE,CLASS=BA,NAME=2, $HASP892 ASID=002A,JOBID=JOB00029 $HASP892 INIT(3) $HASP892 INIT(3) STATUS=INACTIVE,CLASS=CBA,NAME=3, $HASP892 ASID=002B $HASP892 INIT(4) $HASP892 INIT(4) STATUS=INACTIVE,CLASS=DCBA,NAME=4, $HASP892 ASID=002C $HASP892 INIT(5) $HASP892 INIT(5) STATUS=INACTIVE,CLASS=DCBA,NAME=5, $HASP892 ASID=002D /$D I

22 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Symbolic references to files z/OS normally uses symbolic references to files (data sets) rather than actual file names. The use of symbolic references provides a naming redirection between a data set-related name used in a program and the actual data set used during execution of that program.

23 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. How a symbolic file system is used

24 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. JES, job management, and JCL Job control language ( JCL ) is the language used by a batch job to request resources and services from the operating system. Through JCL, you specify: Who you are (important for security reasons). Which resources (programs, files, memory) and services are needed from the system to process your program. The use of JCL is covered in detail in the next module.

25 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Spooling

26 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Two-step job

27 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Job flow through the system During execution, a job goes through the following phases: Input Conversion Processing Output Print (to hardcopy or a console display) Purge

28 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Phases of job flow: input Internal readers (RDR)

29 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Phases of job flow: conversion Merge w/ Proc Libs

30 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Phases of job flow: execution Request Initiators - wlm

31 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Phases of job flow: output and hardcopy Sysout dsn processing - classes

32 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Phases of job flow: purge Clears spool

33 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Job flow through the system Overall Flow

34 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Batch and Job Submission

35 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. JES END /* //

36 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. What is workload manager? Workload manager (WLM): The component of z/OS that manages the processing of workload in the system according to the company’s business goals, such as response time. Also manages the use of system resources, such as processors and storage, to accomplish these goals.

37 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Workload Management Policy for different classes of users

38 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Segregate different classes of uses Casual customer Low priority Gold customer High Priority Customer care High Priority (Business Hours) Data Analysis (Best can do) Business Partner High Priority OD Insurance SLA Highest (1) = Gold Customer High (2) Customer Care Medium (3) Business Partner Low (4) Casual Customer Lowest (5) Data Analysis

39 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Server Process WLM provides for scaling of Application Environments Controller Server Process Server Process Server Process Gold customer High Priority CLAIMS Application Business Partner High Priority Server Process WLM AE1 WLM AE2 Manager Policy Helps meet the goals of transactions by dynamically changing the number of servers on-demand Does this without harming other, more important workload on a system

40 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. z/OS: Prioritizing work across images in a server - IRD Processor resources, data bandwidth and I/O queueing decisions are perfectly balanced across the server to manage diverse workloads within the parameters of stated business goals z10zSeries z/VMz/OS Linux Production WAS DB2 CICS Production WAS DB2 CICS Test & Batch Low Priority MORE

41 Introduction to the new mainframe © Copyright IBM Corp., All rights reserved. Summary Batch processing is a fundamental function of z/OS. z/OS shares with JES the management of jobs and resources. JES receives jobs into the system, schedules them for processing, and controls their output. JES manages jobs in queues. An initiator sets up the necessary environment for running a batch job. Multiple initiators permit the parallel execution of batch jobs. During the life of a job, both JES and the z/OS base control program control different phases of the overall processing.


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