change log_archive_format

Hi all,

on 11g R2 , I have the following :

SQL> recover database using backup controlfile until cancel;

ORA-00334: archived log:

'E:\APP\FLASH_RECOVERY_AREA\ORCL\ARCHIVELOG\2014_07_11\O1_MF_1_5_9VYH39VD_.ARC'

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}

RET

ORA-00334: archived log:

'E:\APP\FLASH_RECOVERY_AREA\ORCL\ARCHIVELOG\2014_07_11\O1_MF_1_5_9VYH39VD_.ARC'

ORA-01112: media recovery not started

But :

SQL> show parameter format

NAME                                 TYPE        VALUE

------------------------------------ ----------- -----------

log_archive_format                   string      ARC%S_%R.%T

nls_date_format                      string

I want to change the log_archive_format to a value that corresponds to O1_MF_1_5_9VYH39VD_.ARC.