1.在主库上，alter system switch logfile;
在备库上:tail -f alert_orac.log 查看：
Tue Jul 12 15:25:01 2011
Media Recovery Log /home/oracle/archive/1_20.dbf
Media Recovery Waiting for thread 1 seq# 21
2。在主库上：
SQL> select open_mode from v$database;
OPEN_MODE
----------
READ WRITE
SQL> select database_role from v$database;
DATABASE_ROLE
----------------
PRIMARY
在备库上：
^X
[oracle@rhel43 bdump]$ sqlplus " / as sysdba"
SQL*Plus: Release 9.2.0.4.0 - Production on Tue Jul 12 15:26:38 2011
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.4.0 - Production
SQL> select open_mode from v$database;
OPEN_MODE
----------
MOUNTED
SQL> select database_role from v$database;
DATABASE_ROLE
----------------
PHYSICAL STANDBY
SQL>