Changing a randomizer when altering an active DEDB area with the DEDB Alter utility and DDL

Instead of using the REPLRAND function of the DEDB Alter utility (DBFUDA00), you can also change the randomizer name for an active DEDB with the ALTERAREA or ADDAREA functions. Only two-stage randomizers can be used with DEDB Alter. The randomizer must not alter the data location of existing areas in the DEDB. This function allows the renaming of a randomizer or preparation for adding new DEDB areas in the future.

When changing a randomizer, the DEDB Alter utility's ALTERAREA, ADDAREA, and REPLRAND functions support DEDB databases with or without sequential dependent (SDEP) segments defined.

If you are adding a Segment Edit/Compression exit routine, during DEDB Alter utility execution the new Segment Edit/Compression exit is not invoked for any areas. The Segment Edit/Compression exit routine is not enabled during DEDB Alter processing. Instead, it is enabled for all DEDB areas after successful DEDB Alter utility completion.

Procedure

Prepare for altering the DEDB randomizer online using ALTERAREA:
1. Assemble and link-edit the changed randomizer into the IMS SDFSRESL or one of the libraries of the IMS SDFSRESL STEPLIB concatenation.
2. If you are adding a Segment Edit/Compression exit routine, assemble and link-edit the Segment Edit/Compression exit routine into the IMS SDFSRESL or one of the libraries of the IMS SDFSRESL STEPLIB concatenation.
  
  If you are using the DEDB Alter utility to add a Segment Edit/Compression exit routine, the Segment Edit/Compression exit routine must be able to handle mixed compressed and non-compressed data in a DEDB database. If data is non-compressed, on read access, it does not expand the non-compressed data, and on write access, it compresses the data and writes out as compressed data. If data is compressed, on read access, it expands the compressed data, and on write access, it compresses the data and writes out as compressed data.
3. Specify the name of the new two-stage randomizer on the RMNAME parameter of the ALTER DATABASE statement for the definition of the DEDB database that is associated with the DEDB area to be altered.
4. If you are adding one or more fields to existing free space that is in a segment of an active DEDB area, use the ALTER TABLE statement with the INTERNALNAME parameter.
5. If you are adding a Segment Edit/Compression exit routine, add the EDITPROC parameter on the ALTER TABLE statement for the DEDB DBD definitions.
6. Alter the SIZE PRIMARY, UOW, and ROOT parameters on the ALTER TABLESPACE statement for the active DEDB area to be altered in the DEDB DBD definitions.
  
  If the DEDB database has SDEP defined, the SIZE PRIMARY parameter of the DEDB area to be altered in the DEDB DBD definitions must be greater than or equal to the SIZE PRIMARY parameter of the active DEDB area.
7. If you are adding a Segment Edit/Compression exit routine, update the EDITPROC parameter on the ALTER TABLE statement.
8. Allocate one or more shadow DEDB area data sets for an active DEDB area to be altered.
  - Allocate one new shadow DEDB area data set if the active DEDB area is defined as a single area data set.
  - Allocate two to six new shadow DEDB area data sets if the active DEDB area is defined as multiple area data sets. The DEDB Alter utility supports six shadow DEDB area data sets, because one shadow image copy data set is required. If you need seven area data sets for multiple area data sets, run the DEDB Create utility to create the seventh area data set after the DEDB Alter utility finishes.
  You can change from single area data set to multiple area data sets at DEDB Alter processing:
  - Allocate two to six new shadow DEDB area data sets if it is to change to multiple area data sets.
  - The DEDB Alter utility supports six shadow DEDB area data sets, because one shadow image copy data set is required.
  You can change from multiple area data sets to single area data set at DEDB Alter processing: allocate one new shadow DEDB area data set if it is to change to single area data set.
  
  The VSAM control interval size must match the SIZE PRIMARY parameter on the ALTER TABLESPACE statement for the active DEDB area to be altered in the new DEDB DBD definitions.
  
  If a DEDB database has SDEP segments defined, the shadow area SDEP part must be greater than or equal to the active area SDEP part, and the shadow area CI size must be greater than or equal to the active area CI size.
9. Register one or more shadow DEDB area data sets for an active DEDB area to be altered to DBRC using the DBRC INIT.ADS command with the SHADOW option.
  The shadow DEDB area data sets are unavailable until the DEDB Alter utility is run to replace the active DEDB area data sets with the shadow DEDB area data sets.
```
INIT.ADS ADDN(name) ADSN(name) AREA(name) DBD(name) SHADOW
```
  The ADDN(name) for the shadow area data set's ddname and the ADSN(name) for the shadow area data set's dsname must be unique for each shadow area data set, and they must be different from those of the associated active area data set.
10. Format one or more shadow DEDB area data sets for the active DEDB area to be altered with the updated SIZE PRIMARY, UOW, and ROOT DEDB area definitions for the DEDB database associated with the active DEDB area to be altered in the IMS directory staging data set using the DEDB Initialization utility (DBFUMIN0).
  After the DEDB Initialization utility runs, the shadow DEDB area data sets remain inaccessible to IMS online systems.
11. Register one of the shadow area data sets, which was allocated in step 1.h, as a shadow image copy data set for an active DEDB area to be altered to DBRC. Use the DBRC INIT.ADS command with SHADOW and IC options to register the shadow image copy data set.
  The shadow image copy data set is unavailable until the DEDB Alter utility is run to replace the active DEDB area data sets with the shadow DEDB area data sets.
```
INIT.ADS ADDN(name) ADSN(name) AREA(name) DBD(name) SHADOW IC
```
  The ADDN(name) for the shadow image copy data set's ddname and the ADSN(name) for the shadow image copy data set's dsname must be different from those of the associated active area data set.
12. By using the DEDB Initialization utility (DBFUMIN0), format one shadow image copy data set for the active DEDB area to be altered with the updated SIZE PRIMARY, UOW, and ROOT DEDB area definitions that are in the IMS directory staging data set. This alters the DEDB database that is associated with the active DEDB area.
  
  After the DEDB Initialization utility runs, the shadow image copy data set remains inaccessible to IMS online systems.
  
  You can format shadow area data sets and shadow image copy data sets for a DEDB area to be altered in one DEDB Initialization utility execution.
  
  After the DEDB Area Initialization utility completes, the shadow area and shadow image copy data sets are marked as SHADOW AVAIL in the RECON.
Prepare to add DEDB areas at the end with the DEDB randomizer online using ADDAREA:
1. Assemble and link-edit the changed randomizer into the IMS SDFSRESL or one of the libraries of the IMS SDFSRESL STEPLIP concatenation.
2. Alter the RMNAME parameter on the ALTER DATABASE statement with a different two-stage DEDB randomizer name. This alters the DEDB database that is associated with the active DEDB area in the DEDB DBD definitions.
3. Alter the SIZE PRIMARY, UOW, and ROOT parameters on the ALTER TABLESPACE statement for the active DEDB area to be altered in the DEDB DBD definitions.
4. Allocate one or more shadow DEDB area data sets for an active DEDB area to be altered.
  - Allocate one new shadow DEDB area data set if an active DEDB area is defined as a single area data set.
  - Allocate 1-7 new shadow DEDB area data sets if an active DEDB area is defined as multiple area data sets.
  The VSAM control interval size must match the SIZE PRIMARY parameter on the ALTER TABLESPACE statement for the active DEDB area to be added in the new DEDB DBD definitions.
5. Register one or more shadow DEDB area data sets for an active DEDB area to be added to DBRC using the DBRC INIT.ADS command with the SHADOW option.
  The shadow DEDB area data sets are unavailable until the DEDB Alter utility is run to add one or more DEDB areas to the end of the DEDB database online
```
INIT.ADS ADDN(name) ADSN(name) AREA(name) DBD(name) SHADOW
```
  The ADDN(name) for the shadow area data set's ddname and the ADSN(name) for the shadow area data set's dsname must be unique for each shadow area data set and they must be different from those of the associated active area data set.
6. Format one or more shadow DEDB area data sets for each DEDB area to be added at the end of the DEDB database in the IMS directory staging data set by using the DEDB Initialization utility (DBFUMIN0).
  After the DEDB Initialization utility runs, the DEDB shadow area data sets remain inaccessible to IMS online systems.
Perform the following steps to alter a DEDB randomizer of a DEDB database online:
1. Assemble and link-edit the changed randomizer into the IMS SDFSRESL or one of the libraries of the IMS SDFSRESL STEPLIB concatenation.
2. Alter the RMNAME parameter on the ALTER DATABASE statement with a different two-stage DEDB randomizer name. This alters the DEDB database that is associated with the active DEDB area in the DEDB DBD definitions.
Run the DEDB Alter utility using the ALTERAREA function to alter an active DEDB area with randomizer change while the DEDB area remains accessible online.
The DEDB Alter utility alters one active DEDB area with randomizer change when the utility is run. The DEDB randomizer is altered as part of the ALTERAREA function of the DEDB Alter utility. The randomizer change does note impact the distribution of data across the DEDB areas that are not altered by the DEDB Alter utility for the DEDB database randomizer to be altered. The new randomizer is not shared with other DEDB databases unless it is an existing randomizer for other DEDB databases.
After the DEDB Alter utility has run successfully, the shadow area data set is promoted to the active area data set. The shadow Image Copy data set becomes the user Image Copy data set. The old active area data set is demoted to the shadow area data set. The old active area data set is not accessible to IMS online systems any longer.
You can delete the old active DEDB area data set in DBRC at a later time when you no longer have a need for the old active DEDB area data set using the DELETE.ADS command.
```
DELETE.ADS ADDN(name) AREA(name) DBD(name)
```
The ADDN(name) is the ddname of the old active area data set.
Run the DEDB Alter utility using the ADDAREA function to add one or more DEDB areas with randomizer change while the DEDB database remains accessible online.
The DEDB Alter utility adds one or more DEDB areas at the end of a DEDB database online when the utility is run. The DEDB randomizer name can be changed by using the ADDAREA function of the DEDB Alter utility. The randomizer change does not affect the distribution of data across the DEDB areas that are not altered by the DEDB Alter utility. The new randomizer is shared with other DEDB databases.
After the DEDB Alter utility completes successfully, the SHADOW status for the area is reset in the RECON. The area is now active and accessible to IMS online systems.