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IDMS

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iain.dk.robertson_at_bt.com. IDMS & REXX in BT. Subject: ... This will look at some techniques used, and some of the ways BT uses REXX to ... – PowerPoint PPT presentation

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Title: IDMS


1
IDMS REXX in BT
  • Iain Robertson
  • IDMS DBA
  • British Telecom
  • iain.dk.robertson_at_bt.com

2
IDMS REXX in BT
  • Subject
  • BT uses REXX to automate various DBA functions
    for its CSS database.
  • This will look at some techniques used, and some
    of the ways BT uses REXX to make the DBAs life
    easier.

3
CSS some background
  • CSS Customer Service System
  • BTs main Customer Facing computer system
  • Order Handling
  • Fault Reporting
  • Billing

4
CSS some background
  • 29 MVS images
  • 3 CVs per image
  • 1 update, 2 Read only
  • 0.5Tb 0.7Tb per database. 13.5Tb total
  • 1,500,000 2,500,000 tasks/day
  • 80,000 lines of REXX code

5
CSS some background
  • Originally, each database had its own DBA team.
  • Now managed by 2 DBAs, plus 3 Central Support
    Team members
  • Therefore, more procedures need to be automated,
    to free DBAs for more important work

6
REXX and CSS
  • REXX applications fall into 3 categories
  • Automating trivial maintenance functions
  • Automating mundane DBA functions
  • Automating emergency functions

7
REXX brief introduction
  • Replacement for CLISTS
  • Can be executed in TSO, or via batch job

8
REXX brief introduction
  • Stem variables
  • EXECIO command
  • String parsing
  • Linking to programs, with optional parameters

9
Trivial functions
  • EXAMPLE
  • Analysing output from utility programs
  • Either user written programs, or CA-supplied
    utilities (IDMSBCF, UCFBATCH)

10
Trivial functions
  • Journal Recovery Flag problem
  • WTOEXIT to write date/time of journal swap
  • When problem occurs, job submitted
    automatically.

11
Trivial functions
  • Job consists of
  • Step to run UCFBATCH to run user written
    checker program in CV
  • Step to run REXX exec to determine
  • Steps to reset journal recovery flag
    (user-written program)

12
Trivial functions
  • REXX exec
  • Reads SYSLST file produced by UCFBATCH step
  • Looks for messages beginning RF issued by the
    checker program
  • Return code based on what it finds
  • 0 Flag has reset itself
  • 1-4 Safe to reset flag on JxJRNL
  • 8 Unable to reset flag

13
Trivial functions
  • Sample SYSLST input to REXX
  • SIGNON UCC7IDM
  • IDMS DC258002 V10 ENTER PASSWORD
  • ?
  • SET OPTIONS NOECHO
  • IDMS DC258003 V10 USER UCC7IDM SIGNED ON LTERM
    UCFL002 AT 015117.17 03.253
  • V10 IDMSPR (MY) ENTER NEXT TASK CODE
  • CHRF 20 30


  • RF000003 RECOVERY FLAG IS ON FOR OFFLOADING
    JOURNAL J4JRNL
  • RF000001 SAFE TO RESET RECOVERY FLAG ON J4JRNL
  • V10 IDMSPR (MY) ENTER NEXT TASK CODE
  • BYE



14
Trivial functions
  • Notes
  • REXX code is very simple
  • Would be possible to do the whole thing in REXX
  • Allocate all necessary files
  • Call UCFBATCH
  • Process output
  • Generate and submit Reset JCL

15
Mundane functions
  • DBA time is valuable shouldnt be wasted on
    functions which can be easily automated
  • DBAN runs
  • Backup scheduling/logging
  • Health checking

16
Mundane functions
  • DBAN Runs
  • CSS database too big to DBAN in one go
  • No Read-only time to run DBANS anyway
  • No space to copy whole database to
  • DBAs could manually recover parts of database to
    copies, and then run DBANs

17
Mundane functions
  • REXX routine written to automate DBANs
  • Parameter driven
  • Areas to DBAN
  • Volumes available to copy DB to, use for sort
    files etc
  • JCL details (jobclass etc)

18
Mundane functions
  • REXX routines
  • Read parameter files
  • Build JCL to
  • Delete old files
  • Copy database files
  • Recover files to a quiesce point (Cogitos SQP
    utility)
  • Run DBN1 DBN2
  • Check output from DBAN jobs

19
Mundane functions
  • Delete old files
  • Generate list of files with name in format
    IDMSPR.DBAN.DFxxxxx'
  • Build IEFBR14 job to delete these

20
Mundane functions
  • Copy database files
  • Copy from IDMSPR.DFxxxxx to IDMSPR.DBAN.DFxxxxx

21
Mundane functions
  • Recover database files
  • Read file containing SQP data
  • Determine which journals to use for recovery
  • Build JCL to
  • Offload current journal if appropriate
  • Rollback DBAN files to SQP

22
Mundane functions
  • Build JCL to run IDMSDBN1 IDMSDBN2
  • Build JCL to check DBN2 output
  • Update DBAN parameters

23
Mundane functions
  • In this way, the whole Database is DBANned
    without any DBA involvement
  • Only notified if there are any problems
  • Process is further parameter driven to allow
    COPYing of files, and CALS runs

24
Mundane functions
  • Also use REXX programs for
  • Reorg functions, including in-flight resizing
  • Building JCL
  • Mapping new files onto existing volumes
  • RACF/Security checking
  • DB Summary reports

25
Emergency functions
  • Database recovery plans important to BT/CSS
  • Hardware consolidation means up to10 CSS images
    on one physical machine
  • Need to automate as much as possible, to relieve
    pressure on DBAs

26
Emergency functions
  • IARS
  • IDMS Automated Recovery System
  • Panels and REXX code to assist with IDMS recovery
  • By File, Area or full Database
  • 25,000 lines of REXX

27
Emergency functions
  • IARS automates all possible functions to recover
    a database
  • Concatenate journals to use for recovery
  • Builds all necessary JCL
  • RollBack
  • RollForward
  • File allocation/formatting
  • DBA simply runs through panels, and
    checks/submits JCL

28
Emergency functions
  • REXX execs will
  • Drive whole recovery process via panels
  • Constructs all needed JCL
  • Determines which archive journals are needed for
    recovery
  • As much as possible automated DBA free to
    concentrate on important issues

29
Summary
  • REXX is a powerful, flexible tool
  • Used with standard/user-written utilities, it can
    greatly reduce a DBAs workload
  • Automation of emergency procedures can reduce
    the risk of errors, and allow better use of DBAs
    time knowledge

30
  • ?
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