Datacom/AD - Using OLREORG with REFGROUP=0 for Disk Backup and Restore tables

Products

• Datacom
• Datacom/DB
• Datacom/AD
• DISK BACKUP AND RESTORE
• Disk Backup and Restore - MVS

Issue/Introduction

OLREORG with REFGROUP=0 requires the Data Space Option (DSOP) attribute set to 4 or 5 instead of the default value of 1. This is done using the steps below.

This reorganization makes use of empty blocks; therefore, the area must contain at least 30% free space.

Cause

The default DSOP attribute for Disk Backup and Restore tables does not support Online Reorg (OLREORG) with REFGROUP=0 (it has value 1). 

Resolution

This process requires PTF RO90201 for Disk Backup and Restore 12.5 to change the DSOP value from 1 to 4 (RANDOM FOR OLREORG). Because this utility makes use of empty blocks, it is necessary that there is at least 20-30% free space in the area being reorganized.

1. Apply all Datacom/DB PTFs related to OLREORG.
2. Verify free space in the database directory (CXX). If the area requires more space, extend the area.
3. Verify the DSOP attribute value is set to 4 (RANDOM FOR OLREORG) by executing a DBUTLTY CXX report for the Disk Backup and Restore database.
4. If the value is not set to RANDOM FOR OLREORG, execute the following DBUTLTY command to change the value dynamically:


   //SYSIN DD * 
     CXXMAINT DBID=<dbid>,AREA=DMS,OPTION=ALTER,DSOP=4
   /*

5. Execute DBUTLTY DATASCAN to rebuild the space index:

   //SYSIN DD *
     DATASCAN DBID=<dbid>,AREA=DMS,OPTION=REBUILD_SPACE_INDEX
   /*

6. If there is insufficient free space (20-30% or more), extend the data area (see article 9503, titled "How to extend a Datacom area while the database is open")
7. Execute DBUTLTY ACCESS...OFF and COMM...CLOSE to close and reopen the database to commit changes:
   

   //SYSIN DD *
     ACCESS DBID=<dbid>,STATUS=OFF,USERS=WAIT 
   COMM   DBID=<dbid>,OPTION=CLOSE
   ACCESS DBID=<dbid>,STATUS=WRITE
   COMM OPTION=CONSOLE,OPTION2='OPEN_BASE <dbid>'
   /*

8. Execute DBUTLTY OLREORG using REFGROUP=0 on each table:
   

   //SYSIN DD *
     OLREORG DBID=<dbid>,TABLE=<ttt>,REFGROUP=0
   /*

Additional Information

The initial OLREORG execution for a table can exceed 24 hours depending on row volume and data fragmentation levels. The OLREORG job can be cancelled or stopped via a REQABORT command and resubmitted at a later time.

The reorganization process generates log area (LXX) records for every row movement, resulting in multiple SPILL requests. Execute SPILL jobs immediately to prevent the Multi-User Facility (MUF) from suspending update activity.

References

• OLREORG (Reorganize a Database Online)