1.改变非归档模式到归档模式:
1)以DBA身份连接数据库，查看是否为归档模式
SQL> conn / as sysdba
SQL> archive log list;
Database log mode No Archive Mode
Automatic archival Disabled
Archive destination USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 31
Current log sequence 33
2)立即关闭数据库
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
3)启动实例并加载数据库到mount状态
SQL> startup mount
ORACLE instance started.
Total System Global Area 1224736768 bytes
Fixed Size 2020384 bytes
Variable Size 318770144 bytes
Database Buffers 889192448 bytes
Redo Buffers 14753792 bytes
Database mounted.
4)更改数据库为归档模式
SQL> alter database archivelog;
Database altered.
5)打开数据库
SQL> alter database open;
SQL> SELECT NAME,created,log_mode FROM v$database;
NAME CREATED LOG_MODE

      ORCL      04-JUN-12 ARCHIVELOG
      Database altered.
 6)启用自动归档   10G之前需要操作
      SQL> alter system archive log start;
 8）查看归档日志的路径和目录
      SQL> show parameter db_recovery_file_dest;
      NAME TYPE VALUE
      ------------------------------------ ----------- ------------------------------
      db_recovery_file_dest string /data/app/oracle/flash_recovery_area
      db_recovery_file_dest_size big integer 2G
 9）修改方法归档日志位置及大小：
      SQL> alter system set db_recovery_file_dest_size=20g;
      SQL> alter system set db_recovery_file_dest='/app/arc';