LOG_ARCHIVE_DEST 和 LOG_ARCHIVE_DEST_n

LOG_ARCHIVE_DEST 和 LOG_ARCHIVE_DEST_n 只能取其一。当LOG_ARCHIVE_DEST设置为非空的时候，那LOG_ARCHIVE_DEST_n就不起作用。反之，如果LOG_ARCHIVE_DEST没有设置，则LOG_ARCHIVE_DEST_n的设置才能生效。如果两类参数均未设定，则系统在启动之后启用缺省值

归档日志不能直接归档到磁带或者裸设备上。
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 any LOG_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 statement ALTER 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.