修改数据库为归档模式的步骤
一、检查当前数据库的设置
    SQL> archive log list;
   Database log mode             No Archive Mode
   Automatic archival             Disable
   Archive destination            USE_DB_RECOVERY_FILE_DEST
   Oldest online log sequence     780
   Next log sequence to archive   783
   Current log sequence           783
二、设置归档路径
   SQL> alter system set  log_archive_dest_1    = 'location=/oraBackup/taurus' scope=both;

三、设置数据库为归档模式
    SQL>shutdown immediate
    SQL>startup mount
    SQL>alter database archivelog;
    SQL>alter database open;
    SQL> archive log list;
       Database log mode              Archive Mode
       Automatic archival             Enabled
       Archive destination            /oraBackup/taurus 
       Oldest online log sequence     780
       Next log sequence to archive   783
       Current log sequence           783
四、确认归档日志正常
     SQL>alter system switch logfile;
    检查/oraBackup/taurus目录下是否有归档日志
     注：alter system archive log current; --先归档再切换
         alter system switch logfile; --先切换至于能不能归档再说