How to keep a certain number of Backup generations?

Document ID : KB000012968
Last Modified Date : 14/02/2018
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Question:

How to keep a certain number of Backup generations?

Answer:

For non-SMS data sets you can limit the number of Backup + Archive generations using IXMAINT parameter COPIES=n. 

However, this will still be the maximum number of generations as expired entries are deleted by IXMAINT anyway. 

 

Similar considerations apply also for SMS data sets. 

The following 2 SMS MC attributes define the maximum number of Backup versions: 

- Number of Backup Versions Data set Exists on Primary (MC). 

- Number of Backup Versions Data set Deleted from Primary (MC). 

Also, you can limit the number of Backup + Archive generations for SMS data sets using IXMAINT parameter COPIES=n,SMSNOSMS 

However, this is again the maximum number of generations as expired entries are deleted by IXMAINT due to following 2 SMS MC attributes: 

- Retain Days Only Backup Version Data set Deleted (MC). 

- Retain Days Extra Backup Versions (MC) 

See CA Disk User Guide, chapter "SMS and IXMAINT" for details on these SMS attributes. 

 

So in summary, you can define a maximum number of Backup/Archive generations, for example 3, but you cannot guarantee or retain 3 generations. 

If an entry is expired, it is deleted anyway.