select min(maxnc), null from  (select max(next_change#) maxnc from v$backup_redolog group by thread#) col min(maxnc) format…

Validate backup – http://www.oracle-scn.com/rman-restore-validate-a-proactive-health-check/

https://clouddba.co/awr-report-analysis-depth-part-1/

https://ss64.com/orav/V$SQLAREA.html