How to keep a certain number of Backup generations?
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.