by default backup area is FRA, It can be change by db_recovery_file_destuse RMAN "FORMAT" parameter, you can set it by "configure" command or in rman commands
FRA contains archivelog ,backupset,datafile,onlinelog folders..
NOW, i specially want to change backup dest. of archvelog to C: (suppose i have C , D, E, F , G) - (i know for archivelogs its log_archive_dest_N command can backup copies to other location but it also goes to default FRA )
backupset to D:
datafile to E:
onlinelog to F:
controlfile to G:
ALL SHOULD CONTAIN ONLY 1 DESTINATION NOT 2 FOR BACKUPS