CA Disk 12.5 : NON SMS number of Backup versions

Document ID : KB000105992
Last Modified Date : 12/07/2018
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Introduction:
In a Backup/Archive run, CA Disk provides comprehensive, efficient, common processing of mixtures of non-VSAM data sets and VSAM clusters. Within a single execution you can back up, archive, delete, and expire different kinds of datasets ( PO - POE - PS - PSE - DA - ISAM - OS CVOL catalog non-VSAM data sets).
You can also back up, archive, delete, and expire VSAM clusters, and back up ICF catalogs.
You can perform backups and archives in either an immediate mode, or in a deferred mode in which the backup or archive is actually done at a later time.
It is possible to do Backup / Archive of both SMS and non-SMS datasets and  CA Disk by default honors the DFSMS Management Class definition and attributes when SMS datasets are managed. 
In case of non-SMS datasets, the product has a great and flexible set of SYSPARMS that can be customized in order to better store the Backup/Archive output data. 
Question:
Performing Backup/Archive of non-SMS datasets, how many Backup/Archive versions are kept by CA Disk and how the Expiration Date of each of them is evaluated?
Environment:
Z/OS - CA Disk 
Answer:
Basically CA Disk provides a main set of SYSPARMS that can be verified and customized in order to provide a correct answer to this question: 

- if DSNDUPVL parm is set to Y then ONLY 1 backup version is stored for each non-SMS dataset that resides on the same volume, regardless of the EXPDT- RETPD parms used during backup run or COPIES=nn subparm used during IXMAINT DSNDELETE run.

- if DSNDUPVL parm is set to N then more parms should be considered as, in this case,  each backup run generates a new backup version that is stored and there isn't any limit to the Backup versions number.  What now should be considered are the RETPD / EXPDT values set during Backup run or the RETRETPD SYSPARM value set (Default 00030). During the DSNINDEX records cleanup the expired Backup copies will be removed using this criteria. 

- as an alternative, if You need to manually limit the number of Backup copies , You can also use IXMAINT DSNDELETE, COPIES=nn and only nn maximum copies will be retained.