ORA-19815: WARNING: db_recovery_file_dest_size

We were getting warning in Alertlog for a database although we were not using FRA.

ORA-19815: WARNING: db_recovery_file_dest_size of 6442450944 bytes is 99.78% used, and has 14326272 remaining bytes available.

Mon Jun 06 12:00:21 2011
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You have following choices to free up space from flash recovery area:
1. Consider changing RMAN RETENTION POLICY. If you are using Data Guard,
   then consider changing RMAN ARCHIVELOG DELETION POLICY.
2. Back up files to tertiary device such as tape using RMAN
   BACKUP RECOVERY AREA command.
3. Add disk space and increase db_recovery_file_dest_size parameter to
   reflect the new space.
4. Delete unnecessary files using RMAN DELETE command. If an operating
   system command was used to delete files, then use RMAN CROSSCHECK and
   DELETE EXPIRED commands.
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Querying FRA showed the following results.

SQL> SELECT substr(name, 1, 30) name, space_limit AS quota,
  2         space_used        AS used,
  3          space_reclaimable AS reclaimable,
  4          number_of_files   AS files
  5    FROM  v$recovery_file_dest ;

NAME                                QUOTA       USED RECLAIMABLE      FILES
------------------------------ ---------- ---------- ----------- ----------
D:\oracle\product\10.2.0/flash 6442450944 6428124672           0        107

rman showed the following
RMAN> list backup summary;

using target database control file instead of recovery catalog

Solution
Run the following as sysdba and restart the instance.
SQL> alter system set db_recovery_file_dest =''
  2  /

System altered.