通过如下测试证明，在Oracle 10g中修改主库的sys用户密码，不会自动更新到备库的数据库和密码文件上。测试过程如下：

1、在主库

$sqlplus / as sysdba

SQL*Plus: Release 10.2.0.5.0 - Production on Fri Aug 12 15:59:14 2011

Connected to:

Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production

SQL> select open_mode from v$database;

OPEN_MODE

----------

READ WRITE

SQL> create user test identified by test;

User created.

SQL> select * from v$pwfile_users;

USERNAME SYSDB SYSOP

------------------------------ ----- -----

SYS TRUE TRUE

SQL> grant connect , alter user to test;

Grant succeeded.

SQL> conn test/test

Connected.

SQL> grant select on dba_users to test;

Grant succeeded.

SQL> conn test/test

Connected.

SQL> col username format a10

SQL> col password format a30

SQL> select password , username from dba_users where username ='TEST';

PASSWORD USERNAME

------------------------------ ----------

7A0F2B316C212D67 TEST

SQL> alter user test identified by test123;

User altered.

SQL> select password , username from dba_users where username ='TEST';

PASSWORD USERNAME

------------------------------ ----------

7C029A1EC393C725 TEST

SQL> conn / as sysdba

Connected.

SQL> show user

USER is "SYS"

SQL> select * from v$pwfile_users;

USERNAME SYSDB SYSOP

---------- ----- -----

SYS TRUE TRUE

通过以上可以看出，如果没有给sysdba或sysoper权限，则用户虽然在数据库字典中密码发生变化，但是不会写到密码文件中。

SQL> grant sysdba to test;

Grant succeeded.

SQL> select * from v$pwfile_users;

USERNAME SYSDB SYSOP

---------- ----- -----

SYS TRUE TRUE

TEST TRUE FALSE

只要给予sysdba权限，才能写到密码文件中；

2、备库的查询结果如下：

$sqlplus sys/abc123@standby as sysdba

SQL*Plus: Release 10.2.0.5.0 - Production on Fri Aug 12 15:57:35 2011

Connected to:

Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production

SQL> select open_mode from v$database;

OPEN_MODE

----------

MOUNTED

SQL> select * from v$pwfile_users;

USERNAME SYSDB SYSOP

------------------------------ ----- -----

SYS TRUE TRUE

在主库给test用户授权sysdba权限前后多次执行以上命令，发现用户根本没有同步过来

3、在主库重新修改Test用户（sysdba）密码

SQL> alter user test identified by test;

User altered.

SQL> select password , username from dba_users where username ='TEST';

PASSWORD USERNAME

------------------------------ ----------

7A0F2B316C212D67 TEST

4、在备库再查询v$pwfile_users

SQL> select * from v$pwfile_users;

USERNAME SYSDB SYSOP

------------------------------ ----- -----

SYS TRUE TRUE