1- in the scheduling there are two tabs Backup Archive Logs and Delete Archive Logs, which both have the delete settings, which one should be setup?
Actually the backup tab doesn't really have delete settings. There is a "delete" setting in the subclient properties which get disabled when the advanced job options delete gets enabled. So only the delete settings from the advanced job options (from the schedule) are then used.
2- Commvault recommendation is to run the crosscheck, however if the log verification/deletion isnt working properly that will never work.
Crosscheck will alert RMAN if logs get deleted so it won't attempt to back up logs that are "missing" There is also an option in the subclient to also skip missing log files (which will send a warning, but still run the backup) But this still potentially leaves a "hole" in the recovery schema. Typically if logs are lost its best to run an incremental asap to fill the gap.
My one recommendation is when using the "delete" from advanced options is to make sure that you also have the "delete logs backed up X times" selected as well, to make sure at least X backups are run for the logs before they are deleted.
Let us know if this helps
Ernst F. Graeler
Senior Engineer III