Database Software

I am looking for some help on what happened to me this morning. The parameter
db_recovery_file_dest_size has been set to 2G. The alert log was flooded with entries like this:
Deleted Oracle managed file E:\ORACLE\PRODUCT\10.1.0\FLASH_RECOVERY_AREA\WQP2\ARCHIVELOG\2006_04_17\O1_MF_1_14902_248DTPLB_.ARC
Deleted Oracle managed file E:\ORACLE\PRODUCT\10.1.0\FLASH_RECOVERY_AREA\WQP2\ARCHIVELOG\2006_04_17\O1_MF_1_14903_248L330Y_.ARC

I wasn't too concerned as I figured the database was doing its job and self managing/cleaning the flashback recovery area. However, when I tried to do a backup I started getting all kinds of errors

Errors in file e:\oracle\product\10.1.0\admin\wqp2\bdump\wqp2_arc1_4240.trc:
ORA-16038: log 3 sequence# 15400 cannot be archived
ORA-19809: limit exceeded for recovery files
ORA-00312: online log 3 thread 1: 'E:\ORACLE\PRODUCT\10.1.0\ORADATA\WQP2\REDO03.LOG'

Mon May 01 07:52:48 2006
ARC0: Evaluating archive log 2 thread 1 sequence 15399
Mon May 01 07:52:48 2006
Errors in file e:\oracle\product\10.1.0\admin\wqp2\bdump\wqp2_arc0_4584.trc:
ORA-19815: WARNING: db_recovery_file_dest_size of 2147483648 bytes is 99.97% used, and has 708608 remaining bytes available.

ORA-19809: limit exceeded for recovery files

ORA-19804: cannot reclaim 4294967296 bytes disk space from 4294967296 limit

I did an RMAN> crosscheck archivelog all and RMAN> delete expired archivelog all

and this didn't help too much. So I increased the size of the size of the recovery area to 4G. I still got these same error messages and eventually had to increase the size to 6G. This seems to have stopped the errors for now.

If I query

SQL> SELECT * FROM V$RECOVERY_FILE_DEST

NAME SPACE_LIMIT SPACE_USED SPACE_RECLAIMABLE NUMBER_OF_FILES
-------------------------------------------------- ----------- ---------- ----------------- --------
E:\oracle\product\10.1.0\flash_recovery_area 6,442,450,944 5,330,496,512 5,131,430,912 81

I see that I have about about 5 gigs of reclaimable space. I have done a RMAN> backup recovery area as well just to be safe.

So my questions are when will I get this space back? Why do I now need 6G of flash area instead of the 2G that has sufficed for months and months? I'd like to know if I need to keep this value at 6G from now on.

The archiver hung as a result of this problem and eventually stopped letting people logon this morning, so I'd like to avoid that again if possible.

Thanks for any feedback.