Datacom ONLINE_AREA_RELEASE and DATAHU Data High Used Mark

Products

• Datacom
• DATACOM - AD
• Datacom/AD
• Datacom/DB

Issue/Introduction

What is the best practice for using the Datacom console-like command ONLINE_AREA_RELEASE (OAR) and the Data High Used Mark (DATAHU)?

ONLINE_AREA_RELEASE needs the Data High Used Mark to be set for the data area. The CXX report shows some areas have a number for HIGH USED TRACK but some have it set to NONE.

Is a DBUTLTY BACKUP/LOAD required to set the Data High Used Mark for an area?

Environment

Release: 15.1

Resolution

The console-like command ONLINE_AREA_RELEASE is used to release unused space at the end of a data area.

There is a section in the Datacom documentation that explains how to use it, see Using ONLINE_AREA_RELEASE.

The command syntax is:
ONLINE_AREA_RELEASE <dbid>,<data-area-name>,<percent-of-never-used-space-to-remove>

It can be issued to the MUF through any of the following ways :

• MVS modify command:
  F mufname,ONLINE_AREA_RELEASE...
  
  
• DBUTLTY function COMM with OPTION=CONSOLE,OPTION2=:
  //SYSIN     DD  *
  COMM OPTION=CONSOLE,OPTION2='ONLINE_AREA_RELEASE...'
/*
  
  
• Using SQL to insert a row into the Dynamic System Table SQL_CONSOLE with DBSQLPR:
  //SYSIN    DD  *
   INSERT INTO SYSADM.SQL_CONSOLE
      VALUES('mufname','ONLINE_AREA_RELEASE...'); 
/*

To use ONLINE_AREA_RELEASE it's a requirement that the data area be currently set with a Data High Used (DATAHU) value. This first requires the CXX-wide option Data High Used Mark (DATAHU) be turned on. 

It is best practice for the CXX-wide option DATAHU be turned on. When doing an upgrade to 15.1 this is done in one of the upgrades jobs with DBUTLTY function:
CXXMAINT OPTION=ALTER,OPTION2=Y_DATAHU                    

Once DATAHU is set in the CXX, the Data High Used Mark for each data area is set when you do a DBUTLTY INIT and LOAD, until then the HIGH USED TRACK will show as NONE in the CXX.

Alternatively, another way to set the Data High Used Mark for an area is by running the DBUTLTY DATASCAN OPTION=SET_DATAHU function.

To set DATAHU for all areas in a dbid use this syntax:
DATASCAN DBID=nnnn,OPTION=SET_DATAHU

To set DATAHU for a single area use this syntax:
DATASCAN DBID=nnnn,OPTION=SET_DATAHU,AREA=aaa 

 

Additional Information

See Datacom documentation sections DATASCAN OPTION=SET_DATAHU, Using DATASCAN to Activate DATAHU Online and Using ONLINE_AREA_RELEASE.