How to Set/Reset log_archive_dest_n parameter

Suppose you have set the parameter log_archive_dest_2 to some network drive /local dirve.
 Now want to remove this parameter


Set the Parameter 
alter system set log_archive_dest_2='location=D:/archivelog' scope = both;

It will over write the default LOG_ARCHIVE_DEST


SQL> show parameter log_archive_dest_2 ;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_2                   string      LOCATION=//host/datab
                                                 ase_backup/rman
log_archive_dest_20                  string
log_archive_dest_21                  string
log_archive_dest_22                  string
log_archive_dest_23                  string
log_archive_dest_24                  string
log_archive_dest_25                  string
log_archive_dest_26                  string
log_archive_dest_27                  string
log_archive_dest_28                  string

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_29                  string
SQL>



To reset
alter system set log_archive_dest_2='' scope = both;

LOG_ARCHIVE_DEST is applicable only if you are running the database in ARCHIVELOG mode or are recovering a database from archived redo logs.LOG_ARCHIVE_DEST is incompatible with the LOG_ARCHIVE_DEST_n parameters, and must be defined as the null string ("") or (' ') when anyLOG_ARCHIVE_DEST_n parameter has a value other than a null string. Use a text string to specify the default location and root of the disk file or tape device when archiving redo log files. (Archiving to tape is not supported on all operating systems.) The value cannot be a raw partition.

If LOG_ARCHIVE_DEST is not explicitly defined and all the LOG_ARCHIVE_DEST_n parameters have null string values, LOG_ARCHIVE_DEST is set to an operating system-specific default value on instance startup.

To override the destination that this parameter specifies, either specify a different destination for manual archiving or use the SQL*Plus statement ARCHIVE LOG START filespec for automatic archiving, where filespec is the new archive destination. To permanently change the destination, use the statementALTER SYSTEM SET LOG_ARCHIVE_DEST = filespec, where filespec is the new archive destination.

Neither LOG_ARCHIVE_DEST nor LOG_ARCHIVE_FORMAT have to be complete file or directory specifiers themselves; they only need to form a valid file path after the variables are substituted into LOG_ARCHIVE_FORMAT and the two parameters are concatenated together.