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IMS 13
IMS 13 Database Versioning and
Alter
© 2012 IBM Corporation
Alter
IMS 13
Database Versioning
08- IMS 13 DB & DBRC: 2
Database Versioning
IMS 13
Database Versioning
� Background
– Customers need to support multiple views of the physical IMS data
– Customers need to make database structure changes while minimizing
the impact to existing application programs that do not need sensitivity to the new physical structure of the database
� Solution
– Enable application programs to use different versions of the same
08- IMS 13 DB & DBRC: 3
– Enable application programs to use different versions of the same physical IMS database
– Maintain multiple views of the physical IMS data in the IMS catalog
– Allow physical database structure changes without modifying all the application programs using the database
� Benefit
– Minimize impact and reduce cost associated with making and
coordinating coding changes to affected application programs when a physical database structure changes
IMS 13
Database Versioning Overview (cont’d)
� Database Versioning supports the following database types
– DEDB
– HDAM
– HIDAM
– PHDAM
– PHIDAM
08- IMS 13 DB & DBRC: 4
� Database Versioning only supports the following database structure changes
– For all supported database types
• Increasing the length of a segment
• Adding a new field to space at the end of a segment
– For Full-Function and HALDB database types
• Adding new field(s) that remap existing field(s) and space at the end of a segment
IMS 13
� Database Versioning must be enabled
� Versioning is at the DBD level
– Users define the version of a database definition on the DBD
– Version numbers must be maintained in incremented values
� Database Versioning requires enablement of the IMS catalog
Database Versioning Overview (cont’d)
08- IMS 13 DB & DBRC: 5
� Database Versioning requires enablement of the IMS catalog
– DBD definitions for versioned databases must be in the IMS catalog
� Application programs scan elect the desired database version
– Specifying the version number on the PCB of the PSB
– Specifying the version number on a DL/I INIT VERSION call
IMS 13
� DFSDFxxx PROCLIB: new DATABASE section keywords
– Specify whether database versioning is enabled and default version
• DBVERSION=
• DBLEVEL=
� Database and Program Generation Statements
– Specify the database version number
Database Versioning Implementation
08- IMS 13 DB & DBRC: 6
– Specify the database version number
• DBD: DBVER=
• PCB: DBVER=
– Override the default versioning specified in DFSDFxxx
• PSBGEN: DBLEVEL=
� “INIT VERSION” DL/I Call
– Overrides the version number that is specified on the PCB statement
– Must be issued before issuing a DL/I DB call to the database
IMS 13
Solution Overview – DFSDFxxx PROCLIB Member
� New keywords added to DATABASE section
– DBVERSION = Y | N
• Enables database versioning
• Database versioning is disabled by default
– DBLEVEL = CURR | BASE
• Ignored when DBVERSION=N
08- IMS 13 DB & DBRC: 7
• Ignored when DBVERSION=N
• CURR (default)
– IMS returns data from all databases using the current DBD version,
which is the current physical level, unless a specific version is specified
• BASE
– IMS returns data from all databases using the lowest DBD version
number retrieved from IMS Catalog, unless a specific version is specified
IMS 13
Solution Overview – DBD Version Number
� If database versioning is enabled, the database version used to return the IMS data is determined by the following hierarchy:
1. DL/I INIT VERSION call
2. PCB Statement DBVER= parameter
08- IMS 13 DB & DBRC: 8
3. PSBGEN Statement DBLEVEL= parameter
4. DFSDFxxx DATABASE Section DBLEVEL= parameter
DL/I INIT VERSION call takes precedence over all other database version number specifications and defaults
IMS 13
Solution Overview – Current IMS Catalog Flow Timestamp instances
DBJK21 DBJK22 DBJK23
ACBLI B
DBJK21 TS0V0DBJK22 TS0V0T1V0
IMS Catalog
DBJK21 DBJK22 DBJK23
DBDLIB
PSBJK
PSBLIB
PSBGEN
--------------------------
PCB
--------------------------
PSB=PSBJK Source
DBJK21
DBD Source
DBJK22
DBJK23
DBDGEN
PSBGEN
ACBGEN
08- IMS 13 DB & DBRC: 9
DBJK21
DBJK22
DBJK23
Application
DBJK21
DBJK22
DBJK23
IMS
DBJK22 TS0V0T1V0DBJK23 TS0V0
PSBJK--------------------------
DBJK21
DBJK22
DBJK23
DBJK21
DBJK22
DBJK23
DLIActive
IMS 13
Solution Overview – Database Versioning Flow Example
DBJK21 V1DBJK22 V1DBJK23 V1
ACBLI B
DBJK21 V0,V1DBJK22 V0,V1
IMS Catalog
DBJK21 V1DBJK22 V1DBJK23 V1
DBDLIB
PSBJK
PSBLIB
PSBGEN
--------------------------
PCB
--------------------------
PSB=PSBJK Source
DBJK21 V1
DBD Source
DBJK22 V1
DBJK23 V1
DBDGEN
PSBGEN
ACBGEN
08- IMS 13 DB & DBRC: 10
DBJK21 V0
DBJK22 V1
DBJK23 V1
Application
DBJK21
DBJK22
DBJK23
IMS
DBJK22 V0,V1DBJK23 V0,V1
PSBJK--------------------------
DBJK21 V0
DBJK22
DBJK23 V1
DBJK21 V0
DBJK22 V1
DBJK23 V1
DLI
Retrieve from Catalog
DBJK21 V1
DBJK22 V1
DBJK23 V1
Active
IMS 13
Solution Overview – Database Versioning Flow Example
DBJK21 V2DBJK22 V2DBJK23 V2
ACBLI B
DBJK21 V0,V1,V2DBJK22 V0,V1,V2
IMS Catalog
DBJK21 V2DBJK22 V2DBJK23 V2
DBDLIB
PSBJK
PSBLIB
PSBGEN
DBLEVEL=BASE
--------------------------
PCB
--------------------------
PSB=PSBJK Source
DBJK21 V2
DBD Source
DBJK22 V2
DBJK23 V2
DBDGEN
PSBGEN
ACBGEN
08- IMS 13 DB & DBRC: 11
DBJK21 V1
DBJK22 V0
DBJK23 V2
Application
DBJK21
DBJK22
DBJK23
IMS
DBJK22 V0,V1,V2DBJK23 V0,V1,V2
PSBJK--------------------------
DBJK21 V1
DBJK22
DBJK23 V2
DBJK21 V2
DBJK22 V2
DBJK23 V2
DBJK21 V1
DBJK22 V0
DBJK23 V2
DLI
Retrieve from Catalog
Active
IMS 13
Solution Overview – Database Versioning Flow Example
DBJK21 V3DBJK22 V3DBJK23 V3
ACBLI B
DBJK21 V0,V1,V2,V3DBJK22 V0,V1,V2,V3
IMS Catalog
DBJK21 V3DBJK22 V3DBJK23 V3
DBDLIB
PSBJK
PSBLIB
PSBGEN
DBLEVL=CURR
--------------------------
PCB
--------------------------
PSB=PSBJK Source
DBJK21 V3
DBD Source
DBJK22 V3
DBJK23 V3
DBDGEN
PSBGEN
ACBGEN
08- IMS 13 DB & DBRC: 12
DBJK21 V1
DBJK22 V3
DBJK23 V2
Application
DBJK21
DBJK22
DBJK23
IMS
DBJK22 V0,V1,V2,V3DBJK23 V0,V1,V2,V3
PSBJK--------------------------
DBJK21 V1
DBJK22
DBJK23 V2
DBJK21 V3
DBJK22 V3
DBJK23 V3
DBJK21 V3
DBJK22 V2
DBJK23 V1
DLI
Retrieve from Catalog
Active
IMS 13
Solution Overview – Database Versioning Flow Example
DBJK21 V3DBJK22 V3DBJK23 V3
ACBLI B
DBJK21 V0,V1,V2,V3DBJK22 V0,V1,V2,V3
IMS Catalog
DBJK21 V3DBJK22 V3DBJK23 V3
DBDLIB
PSBJK
PSBLIB
PSBGEN
DBLEVL=CURR
--------------------------
PCB
--------------------------
PSB=PSBJK Source
DBJK21 V3
DBD Source
DBJK22 V3
DBJK23 V3
DBDGEN
PSBGEN
ACBGEN
08- IMS 13 DB & DBRC: 13
DBJK21 V1
DBJK22 V3
DBJK23 V2
Application
DBJK21
DBJK22
DBJK23
IMS
DBJK22 V0,V1,V2,V3DBJK23 V0,V1,V2,V3
PSBJK--------------------------
DBJK21 V1
DBJK22
DBJK23 V2
DBJK21 V3
DBJK22 V3
DBJK23 V3
DBJK21 V3
DBJK22 V2
DBJK23 V1
DLI
Retrieve from Catalog
INIT VERSION(
DBJK21=3
DBJK22=2
DBJK23=1)
Active
Override
PSBGEN
IMS 13
� Enable IMS Catalog
– Populate catalog with DBD version definitions
– Before Database Versioning is enabled for a database, IMS continues
to only recognize only the current active database definition
� Recommendations
– In preparation to enable Database Versioning, specify the new DBD and PSB statement versioning attributes
Database Versioning Migration Considerations
08- IMS 13 DB & DBRC: 14
and PSB statement versioning attributes
• Use the DBLEVEL=CURR setting so all applications access the
databases at latest levels by default
• Use the PCB DBVER= parameter if an application needs to continue using an old version of a database
– All systems in an IMSplex must be running IMS 13
– Enable Database Versioning
IMS 13
HALDB Alter
08- IMS 13 DB & DBRC: 15
HALDB Alter
IMS 13
HALDB Alter
� Background
– Customers face the challenge of maintaining online database availability
while making structural changes to a HALDB database
– Customers cannot make structural changes to a Full Function HALDB without taking the database offline to unload/reload
� Solution
08- IMS 13 DB & DBRC: 16
– Structural changes can be made to DBD segment definitions
– Online reorganization command must be issued to apply the structural
change to the HALDB database
– Online change command must be issued to activate the new ACBLIB
member
� Benefit
– Make structural changes to a database while maintaining database availability
IMS 13
HALDB Alter Prerequisites
� Software requirements
– CSL
• SCI
• OM
– DBRC RECON MINVERS (‘13.1’)
08- IMS 13 DB & DBRC: 17
– DBRC RECON MINVERS (‘13.1’)
� Hardware requirements
– Same as base IMS 13
IMS 13
HALDB Alter Overview
� Structural changes can be made to HALDB databases while the database remains online
– Add a new field to space at the end of an existing segment
– Increase the length of an existing segment
– Define new fields that remap existing fields and space in an existing segment
08- IMS 13 DB & DBRC: 18
existing segment
� HALDB Alter is only supported for database types:
– PHDAM
– PHIDAM
IMS 13
HALDB Alter Overview (cont’d)
� After changes are made to the DBD segment definition
– Type-2 Online Reorg command is used to alter a database from the current structure to the new structure
• Type-1 command /INITIATE OLREORG does not support altering a HALDB
– Online Change commands are used to bring the changed ACBLIB
08- IMS 13 DB & DBRC: 19
– Online Change commands are used to bring the changed ACBLIB DBD member online
– Application programs can start using the new database structure
IMS 13
FIELD 1
FIELD 2 Space
FIELD 2 SpaceNew
FIELD 3
Add a new field to space at the end of a segment
Example 1
FIELD 1
08- IMS 13 DB & DBRC: 20
FIELD 1
FIELD 3
Example 2
FIELD 1 FIELD 2
FIELD 2 Space
New
FIELD 3Space
IMS 13
FIELD 1
FIELD 2
New SpaceFIELD 2
Increase the length of an existing segment
Example 1
FIELD 1
08- IMS 13 DB & DBRC: 21
FIELD 1
Example 2
FIELD 1 FIELD 2
FIELD 2
New Space
Space
Space
IMS 13
FIELD 1
FIELD 2
SpaceFIELD 2
Define new fields to remap existing fields & space in a segment
Example 1
FIELD 1
Overlay
FIELD 3
New
FIELD 5
Overlay
FIELD 4
Space
08- IMS 13 DB & DBRC: 22
FIELD 1
Example 2
FIELD 1 FIELD 2
FIELD 2
SpaceNew
FIELD 4
Space
Overlay
FIELD 3Space
IMS 13
HALDB Alter Preparation
� Change the DBD source code
– Define new fields in space at end of segment
• Specify new FIELD statements
– Increase the length of a segment
• Specify new length in the BYTES= parameter of SEGM statement
– Overlay existing fields and space in a segment
08- IMS 13 DB & DBRC: 23
– Overlay existing fields and space in a segment
• Specify overlay and new FIELD statements
� Run DBDGEN
– Changed DBD used as input
� Run ACBGEN
– //IMSACB DD pointing to the staging ACBLIB
IMS 13
HALDB Alter Online Processing
� Online reorg is used to alter the structure of a HALDB database
– The input DBD comes from the current version in the active ACBLIB
– The output DBD comes from the new version in a staging ACBLIB
� Delta files are built to represent the changes between the active/input DMB and the staged/output DMB
08- IMS 13 DB & DBRC: 24
active/input DMB and the staged/output DMB
� All database partitions are included in the reorg process
� Application programs accessing the existing database continue running using the current version of the DBD
� Max of 10 TCBs will be scheduled concurrently for an ALTER process, if necessary
IMS 13
HALDB Alter Example
� Update DBD source for MASTER database
– Increases the size of segment B from 30 bytes to 40 bytes
� Run DBDGEN
� Run ACBGEN(s) into staging ACB library
� DBRC CHANGE.PART ALTERSZE() to alter BLK or CI size, if necessary
� Issue INIT OLREORG NAME(MASTER) OPTION(ALTER)
– Builds the input DMB control blocks using the active ACBLIB
A
B
C
MASTER DB
08- IMS 13 DB & DBRC: 25
– Allocates the staging ACBLIB
– Builds the output DMB control blocks using the staging ACBLIB
– Allocates the output database data set(s)
� Make updates to affected application programs
� Backup active ACBLIB members affected by changes
� Stop MASTER DB access
� Perform Online Change
� Start MASTER DB access
New DMBIMS
Staging ACBLIB
Old DMBActive
ACBLIB
Input data sets
A – J, X
Output data sets
M – V, Y
OLR
IMS 13
Fast Path DEDB Alter
08- IMS 13 DB & DBRC: 26
Fast Path DEDB Alter
IMS 13
DEDB Alter
� IMS 13 adds ability to dynamically change DEDB specifications
– Users can dynamically change UOW, SIZE, ROOT, Randomizer while DEDB is online
– New DEDB Alter utility is used for DEDB changes
– DRD is not required for DEDB Alter
– Supports VSO Areas if /VUNLOAD is done before DEDB Alter is executed
08- IMS 13 DB & DBRC: 27
� Benefits
– Improved management of DEDB definitions
• Eliminate system down time for modifications to DEDB definitions
• Improve data availability since changes are done while DEDB is online
IMS 13
Preparation for DEDB Alter
� DEDB Alter function changes:
– ALTERAREA area_name
• Modify the active DEDB AREA statement (SIZE, UOW, ROOT, RMNAME)
– REPLRAND
• Modify the active DEDB AREA statement (RMNAME)
08- IMS 13 DB & DBRC: 28
� IMS Gens needed for ALTERAREA, REPLRAND:
– Run the DBDGEN utility to create new DEDB DBD definitions
– Run the ACBGEN utility for all PSBs that reference changed DEDB DBD
• New ACBs are added to staging ACBLIB data sets
IMS 13
New DEDB Alter Utility (DBFUDA00)
� DEDB Alter utility supports three functions
– ALTERAREA area_name
• Allow DBD parms (UOW, ROOT, SIZE, RMNAME) to change values
– REPLRAND
08- IMS 13 DB & DBRC: 29
• Allow DBD parm (RMNAME) to change Randomizer name
� The following requirements apply when using the DEDB Alter utility:
– DEDB databases must be registered to DBRC.
– The randomizer must be a genuine two-stage randomizer and defined as a two-stage randomizer in the DBD.
– To run the DEDB Alter utility, all IMS™ data-sharing systems must be at the IMS Version 13 or later level. The MINVERS value in the RECON data set must be 13.1 or later.
IMS 13
Preparation for DEDB Alter
� Allocate Shadow Area data sets
– Shadow Area data sets used for migrating existing data from Active Areas
– Single Area Data Sets (SADS)
• Single Shadow data set is required
– Multiple Area Data Sets (MADS)
• 2 to 7 Shadow data sets are required
08- IMS 13 DB & DBRC: 30
• 2 to 7 Shadow data sets are required
– SADS can become MADS and MADS can become SADS after DEDB Alter
• Depends on the number of allocated Shadow Area data sets
– Shadow data sets are not accessible by the IMS System
• Accessible to DEDB Alter utility only
� Allocate Shadow IC data sets:
– Created while DEDB Alter migrates data to Shadow Area data sets
IMS 13
Preparation for DEDB Alter
� Register Shadow data sets to DBRC (INIT.ADS)
>>-INIT.ADS--ADDN(shadowname)--ADSN(shadowname)--AREA(name)--DBD(name)--->
08- IMS 13 DB & DBRC: 31
.-UNAVAIL-----.
>--+---------+-------+---------------+--------------------------><
` '-AVAIL----------' '-SHADOW------+-------'
'-IC----'
IMS 13
Preparation for DEDB Alter
� Format Shadow data sets with DEDB Area Init Util (DBFUMIN0)
– Shadow Area data sets and Shadow IC data sets formatted
– Two new control cards:
– ACTIVE = Format Area data sets for DEDB Area
– SHADOW = Format Shadow Area and Shadow IC data sets
– Formats Active or Shadow data sets in one execution, but not both
08- IMS 13 DB & DBRC: 32
– Formats Active or Shadow data sets in one execution, but not both
– When DBRC=Y, formats both Shadow Area and Shadow IC in one execution
� New ACB from Staging ACBLIB used for formatting
� After utility completes, flags are set in RECON:
– Shadow Area data sets are marked “SHADOW AVAIL”
– Shadow IC Area data sets are marked “SHADOW IC AVAIL”
� Shadow data sets must be formatted before DEDB Alter utility runs
IMS 13
Preparation for DEDB Alter
� ACBLIB staging library needs dynamic allocation member
– Create a DFSMDA member for the ACBLIB staging library
• If one does not already exist
– Sample JCL:
08- IMS 13 DB & DBRC: 33
DFSMDA TYPE=INITIAL DFSMDA TYPE=IMSACB,DSNAME=STAGING.LIBRARY DFSMDA TYPE=FINAL
� New DEDB Alter Datasharing Group Name
– Defined in <SECTION=FASTPATH> in DFSDFxxx Proclib Member
– ALTERGRP=nnnnn (Prefixed by DBFnnnnn)
– Used for datasharing communications between datasharing partners
IMS 13
DEDB Area Structure
Root Addressable Part
(Roots and Direct Dependents)V
S
A
M
D
BUnit of WorkUnit of Work
Unit of Work
ROOT
08- IMS 13 DB & DBRC: 34
Independent Overflow Part
(Overflow from Root Addressable Part)
Reorganization Unit of Work
Sequential Dependent Part
(Sequential Dependents Only)
M
D
E
F
I
N
E
B
D
No longer used
Unit of Work
Not Allowed with
ALTERAREA
Allowed with
REPLRAND
ROOT
SDEP DDEP
DDEP
DDEP
IMS 13
DEDB Alter Summary
� IMS 13 adds ability to dynamically change DEDB specifications
– Users can dynamically change UOW, SIZE, ROOT and Randomizer while DEDB is online
– New DEDB Alter utility is used to make changes
� Benefits
– Improved management of DEDB definitions
08- IMS 13 DB & DBRC: 35
– Improved management of DEDB definitions
• Eliminate system down time for modifications to DEDB definitions
• Improve data availability since changes are done while DEDB is online
