RMAN> list backup;

specification does not match any backup in the repository

RMAN> configure retention policy to redundancy 2;

old RMAN configuration parameters:
CONFIGURE RETENTION POLICY TO REDUNDANCY 2;
new RMAN configuration parameters:
CONFIGURE RETENTION POLICY TO REDUNDANCY 2;
new RMAN configuration parameters are successfully stored

RMAN> backup full database;

Starting backup at 10-JAN-19
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00002 name=/oradata/MIN18/data_D-MIN18_I-2460040847_TS-SYSAUX_FNO-2_03tmvlae
input datafile file number=00001 name=/oradata/MIN18/data_D-MIN18_I-2460040847_TS-SYSTEM_FNO-1_04tmvlah
input datafile file number=00003 name=/oradata/MIN18/data_D-MIN18_I-2460040847_TS-UNDOTBS1_FNO-3_05tmvlai
input datafile file number=00004 name=/oradata/MIN18/data_D-MIN18_I-2460040847_TS-USERS_FNO-4_06tmvlaj
channel ORA_DISK_1: starting piece 1 at 10-JAN-19
channel ORA_DISK_1: finished piece 1 at 10-JAN-19
piece handle=/oracle_backup/MIN18/0stn0u5n_1_1 tag=TAG20190110T232439 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:15
Finished backup at 10-JAN-19

Starting Control File and SPFILE Autobackup at 10-JAN-19
piece handle=/oracle_backup/MIN18/c-2460040847-20190110-0b comment=NONE
Finished Control File and SPFILE Autobackup at 10-JAN-19

RMAN> backup full database;

Starting backup at 10-JAN-19
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00002 name=/oradata/MIN18/data_D-MIN18_I-2460040847_TS-SYSAUX_FNO-2_03tmvlae
input datafile file number=00001 name=/oradata/MIN18/data_D-MIN18_I-2460040847_TS-SYSTEM_FNO-1_04tmvlah
input datafile file number=00003 name=/oradata/MIN18/data_D-MIN18_I-2460040847_TS-UNDOTBS1_FNO-3_05tmvlai
input datafile file number=00004 name=/oradata/MIN18/data_D-MIN18_I-2460040847_TS-USERS_FNO-4_06tmvlaj
channel ORA_DISK_1: starting piece 1 at 10-JAN-19
channel ORA_DISK_1: finished piece 1 at 10-JAN-19
piece handle=/oracle_backup/MIN18/0utn0u6g_1_1 tag=TAG20190110T232504 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:15
Finished backup at 10-JAN-19

Starting Control File and SPFILE Autobackup at 10-JAN-19
piece handle=/oracle_backup/MIN18/c-2460040847-20190110-0c comment=NONE
Finished Control File and SPFILE Autobackup at 10-JAN-19

RMAN> backup full database;

Starting backup at 10-JAN-19
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00002 name=/oradata/MIN18/data_D-MIN18_I-2460040847_TS-SYSAUX_FNO-2_03tmvlae
input datafile file number=00001 name=/oradata/MIN18/data_D-MIN18_I-2460040847_TS-SYSTEM_FNO-1_04tmvlah
input datafile file number=00003 name=/oradata/MIN18/data_D-MIN18_I-2460040847_TS-UNDOTBS1_FNO-3_05tmvlai
input datafile file number=00004 name=/oradata/MIN18/data_D-MIN18_I-2460040847_TS-USERS_FNO-4_06tmvlaj
channel ORA_DISK_1: starting piece 1 at 10-JAN-19
channel ORA_DISK_1: finished piece 1 at 10-JAN-19
piece handle=/oracle_backup/MIN18/10tn0u72_1_1 tag=TAG20190110T232522 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:15
Finished backup at 10-JAN-19

Starting Control File and SPFILE Autobackup at 10-JAN-19
piece handle=/oracle_backup/MIN18/c-2460040847-20190110-0d comment=NONE
Finished Control File and SPFILE Autobackup at 10-JAN-19

RMAN> backup full database;

Starting backup at 10-JAN-19
using channel ORA_DISK_1
skipping datafile 1; already backed up 3 time(s)
skipping datafile 2; already backed up 3 time(s)
skipping datafile 3; already backed up 3 time(s)
skipping datafile 4; already backed up 3 time(s)
Finished backup at 10-JAN-19

RMAN>