My full db backup failed and I am not sure what the problem is.
Initially, we performed our first backup on 9/30 and it was a success.
We scheduled it for a daily backup using the same setting and they all failed as you can see with the screen shot below.

I am not a DBA and we don't have a DBA here. I am trying to keep everything intact without breaking anything.
Thanks.
Here's the failed log.
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using target database control file instead of recovery catalog
connected to target database: april (DBID=1234567890, not open)
echo set on
run {
allocate channel oem_disk_backup device type disk;
recover
allocated channel: oem_disk_backup
channel oem_disk_backup: sid=100 devtype=DISK
no copy of datafile 2 found to recover
no copy of datafile 1 found to recover
Starting recover at 05-OCT-16
no copy of datafile 4 found to recover
channel oem_disk_backup: specifying datafile copies to recover
channel oem_disk_backup: starting incremental datafile backupset restore
recovering datafile copy fno=00003 name=C:\ORACLE\PRODUCT\10.2.0\FLASH_RECOVERY_AREA\april\DATAFILE\O1_MF_SYSAUX_CYYQSFMR_.DBF
recovering datafile copy fno=00005 name=C:\ORACLE\PRODUCT\10.2.0\FLASH_RECOVERY_AREA\april\DATAFILE\O1_MF_EXAMPLE_CYYQTB64_.DBF
channel oem_disk_backup: reading from backup piece C:\ORACLE\PRODUCT\10.2.0\FLASH_RECOVERY_AREA\april\BACKUPSET\2016_10_04\O1_MF_
piece handle=C:\ORACLE\PRODUCT\10.2.0\FLASH_RECOVERY_AREA\april\BACKUPSET\2016_10_04\O1_MF_NNND1_TAG20161004T030050_CZ6NX91V_.BKP
channel oem_disk_backup: restored backup piece 1
channel oem_disk_backup: restore complete, elapsed time: 00:00:03
Finished recover at 05-OCT-16
Starting backup at 05-OCT-16
no parent backup or copy of datafile 4 found
no parent backup or copy of datafile 2 found
no parent backup or copy of datafile 1 found
channel oem_disk_backup: starting datafile copy
input datafile fno=00004 name=E:\ORACLE\PRODUCT\10.2.0\ORADATA\april\USERS01.DBF
RMAN-03009: failure of backup command on oem_disk_backup channel at 10/05/2016 03:00:54
ORA-19809: limit exceeded for recovery files
ORA-19804: cannot reclaim 3287285760 bytes disk space from 6442450944 limit
continuing other job steps, job failed will not be re-run
channel oem_disk_backup: starting datafile copy
input datafile fno=00002 name=E:\ORACLE\PRODUCT\10.2.0\ORADATA\april\UNDOTBS01.DBF
ORA-19809: limit exceeded for recovery files
RMAN-03009: failure of backup command on oem_disk_backup channel at 10/05/2016 03:00:57
channel oem_disk_backup: starting piece 1 at 05-OCT-16
input datafile fno=00005 name=E:\ORACLE\PRODUCT\10.2.0\ORADATA\april\EXAMPLE01.DBF
input datafile fno=00003 name=E:\ORACLE\PRODUCT\10.2.0\ORADATA\april\SYSAUX01.DBF
channel oem_disk_backup: specifying datafile(s) in backupset
channel oem_disk_backup: starting incremental level 1 datafile backupset
ORA-19804: cannot reclaim 1572864000 bytes disk space from 6442450944 limit
continuing other job steps, job failed will not be re-run
channel oem_disk_backup: backup set complete, elapsed time: 00:00:15
piece handle=C:\ORACLE\PRODUCT\10.2.0\FLASH_RECOVERY_AREA\april\BACKUPSET\2016_10_05\O1_MF_NNND1_TAG20161005T030050_CZ9999RV_.BKP
channel oem_disk_backup: finished piece 1 at 05-OCT-16
input datafile fno=00001 name=E:\ORACLE\PRODUCT\10.2.0\ORADATA\april\SYSTEM01.DBF
channel oem_disk_backup: starting datafile copy
RMAN-03009: failure of backup command on oem_disk_backup channel at 10/05/2016 03:01:15
ORA-19804: cannot reclaim 534773760 bytes disk space from 6442450944 limit
ORA-19809: limit exceeded for recovery files
continuing other job steps, job failed will not be re-run
including current control file in backupset
channel oem_disk_backup: specifying datafile(s) in backupset
channel oem_disk_backup: starting incremental level 1 datafile backupset
channel oem_disk_backup: starting piece 1 at 05-OCT-16
including current SPFILE in backupset
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of backup command on oem_disk_backup channel at 10/05/2016 03:01:20
ORA-19804: cannot reclaim 52428800 bytes disk space from 6442450944 limit
exit;
RMAN-00571: ===========================================================
released channel: oem_disk_backup
ORA-19809: limit exceeded for recovery files