在Oracle10g中，只要启动数据库的归档模式，Oracle就会启用自动归档，从而避免了10g以前由于用户疏忽所带来的一系列问题。

$ sqlplus "/ as sysdba"

SQL*Plus: Release 10.1.0.3.0 - Production on Wed Apr 13 09:53:25 2005

Copyright (c) 1982, 2004, Oracle.  All rights reserved.


Connected to:
Oracle Database 10g Enterprise Edition Release 10.1.0.3.0 - 64bit Production
With the Partitioning and Data Mining options

SQL> archive log list;
Database log mode              No Archive Mode
Automatic archival             Disabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     25
Current log sequence           27
SQL> show parameter log_archive_start

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
log_archive_start                    boolean     FALSE
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup mount;
ORACLE instance started.

Total System Global Area 3204448256 bytes
Fixed Size                  1304912 bytes
Variable Size             651957936 bytes
Database Buffers         2550136832 bytes
Redo Buffers                1048576 bytes
Database mounted.
SQL> alter database archivelog;

Database altered.

SQL> alter database open;

Database altered.

SQL> archive log list;
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     25
Next log sequence to archive   27
Current log sequence           27
SQL>