SYS@boston>SELECT ESTIMATED_FLASHBACK_SIZE FROM V$FLASHBACK_DATABASE_LOG;

ESTIMATED_FLASHBACK_SIZE
------------------------
                45195264

SYS@boston>select name, value, issys_modifiable from v$parameter where  name='db
_recovery_file_dest_size';

NAME
--------------------------------------------------------------------------------

VALUE
--------------------------------------------------------------------------------

ISSYS_MOD
---------
db_recovery_file_dest_size
9663676416
IMMEDIATE


SYS@boston>select * from v$recovery_file_dest;

NAME
--------------------------------------------------------------------------------

SPACE_LIMIT SPACE_USED SPACE_RECLAIMABLE NUMBER_OF_FILES
----------- ---------- ----------------- ---------------
D:\Ora102\chicago\boston_recover\
 9663676416 1671241216        1103842304              50


SYS@boston>select * from v$flash_recovery_area_usage;

FILE_TYPE    PERCENT_SPACE_USED PERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES
------------ ------------------ ------------------------- ---------------
CONTROLFILE                   0                         0               0
ONLINELOG                   .04                         0               1
ARCHIVELOG                  .16                       .01              21
BACKUPPIECE               16.84                     11.41              22
IMAGECOPY                     0                         0               0
FLASHBACKLOG                .25                         0               6

6 rows selected.

SYS@boston>