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TECH TIP: Using DBCOPY's "asynchronous processing" to minimize the time being needed to create your Image Copy backup files 

Apr 13, 2017 05:13 AM

Although Image Copy files already can be created very fast by using CA's Database Copier (DBCOPY), a large number of database datasets to be image copied still results in much time being needed to create all the backup files. DBCOPY's "asynchronous processing" significantly shortens the overall elapsed time being needed to image copy an entire group of related database datasets.

 

What does it do?

When more than one database dataset has to be image copied in one single DBCOPY jobstep, all backup datasets will be created successively one after another, i.e. the subtask to create the next image copy doesn't start before the previous subtask has finished.

With "asynchronous processing" switched on, the subtasks to copy the different database datasets are running in parallel, using resources which are currently not needed by any other subtask. While the time being needed for each single image copy task is not reduced, the overall elapsed time for all overlapping subtasks actually will be much shorter.

 

How will it be activated? 

To image copy more than one database dataset in one single DBCOPY step, use  "FUNCTION=ACOPY" (instead of "FUNCTION=COPY") for those datasets which should be image copied concurrently.

For more details about "DBCOPY asynchronous processing" see

https://docops.ca.com/ca-database-management-solutions-for-ims-for-z-os/19-0/en/backing-up-and-recovering-databases/ca-database-copier-for-ims/using-ca-database-copier/creating-asynchronous-image-copies

 

Limitations

Because several image copy subtasks are running concurrently, the z/OS address space could become short-on-storage, resulting in abending the entire DBCOPY execution. Use DBCOPY option TASKLIMIT=n  to limit the max number of concurrently running subtasks to avoid short-on-storage conditions with asynchronous processing.

For more details about the TASKLIMIT option see 

https://docops.ca.com/ca-database-management-solutions-for-ims-for-z-os/19-0/en/backing-up-and-recovering-databases/ca-database-copier-for-ims/customizing-ca-database-copier-jcl/ca-database-copier-control-statements-reference/tasklimit-dbc-define-task-limits

 

Example

 

//DBCOPY    EXEC PGM=IDIDBO,REGION=0M                               

//STEPLIB   DD DSN=ca.imstools.CIMTLOAD,DISP=SHR              

//          DD DISP=SHR,DSN=ims.SDFSRESL                       

//DFSRESLB  DD DISP=SHR,DSN=ims.SDFSRESL

//IMS       DD DISP=SHR,DSN=ims.DBDLIB                                          

//dd1       DD DISP=SHR,DSN=hlq.dbd.dd1                      

//dd2       DD DISP=SHR,DSN=hlq.dbd.dd2                      

//ddn       DD DISP=SHR,DSN=hlq.dbd.ddn                      

//DBC1      DD DSN= hlq.dbd.dd1.DBC,DISP=(,CATLG,DELETE), 

//             STORCLAS=***,SPACE=(CYL,(n,m),RLSE)        

//DBC2      DD DSN= hlq.dbd.dd2.DBC,DISP=(,CATLG,DELETE), 

//             STORCLAS=***,SPACE=(CYL,(n,m),RLSE) 

//DBCn      DD DSN= hlq.dbd.ddn.DBC,DISP=(,CATLG,DELETE), 

//             STORCLAS=***,SPACE=(CYL,(n,m),RLSE)                

//DBOMSGS   DD SYSOUT=*                                             

//DBORPTS   DD SYSOUT=*                                             

//DBOCTRL   DD *                                                    

FUNCTION=ACOPY,DBDNAME=dbd1,DDNAME=dd1,DBRC=N,COPY1DDNAME=DBC1,    

TASKLIMIT=nn   

FUNCTION=ACOPY,DBDNAME=dbd2,DDNAME=dd2,DBRC=N,COPY1DDNAME=DBC2,    

TASKLIMIT=nn   

FUNCTION=ACOPY,DBDNAME=dbdn,DDNAME=ddn,DBRC=N,COPY1DDNAME=DBCn,    

TASKLIMIT=nn   

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