搭建實時同步data guard的最高可用-切換主備
首先保證主庫在歸檔模式下:錯過N次了
準備二臺機器(hostname gw hosts ech0)host-only
[root@node1 ~]# ifconfig
eth0????? Link encap:Ethernet? HWaddr 08:00:27:9C:CC:51?
????????? inet addr:192.168.56.147? Bcast:192.168.56.255? Mask:255.255.255.0
????????? inet6 addr: fe80::a00:27ff:fe9c:cc51/64 Scope:Link
????????? UP BROADCAST RUNNING MULTICAST? MTU:1500? Metric:1
????????? RX packets:750606 errors:0 dropped:0 overruns:0 frame:0
????????? TX packets:132742 errors:0 dropped:0 overruns:0 carrier:0
????????? collisions:0 txqueuelen:0
????????? RX bytes:179921301 (171.5 MiB)? TX bytes:2845074889 (2.6 GiB)

eth0:1??? Link encap:Ethernet? HWaddr 08:00:27:9C:CC:51?
????????? inet addr:192.168.1.147? Bcast:192.168.1.255? Mask:255.255.255.0
????????? UP BROADCAST RUNNING MULTICAST? MTU:1500? Metric:1

?主庫
?ip 192.168.1.147 node1.dg.com?? 安裝好ORACLE,正常運行的數據庫
?ipadd:? 192.168.1.147? gw:192.168.1.1
???? oracle sid: orcl?
???? database name :orcl
???? service? name :orcl??
備庫
ip 192.168.1.157 node1.dg.com?? 只安裝軟件就可以了
???? ipadd:? 192.168.1.157
???? gw:192.168.1.1
???? oracle sid: orcl02 ?
???? database name :orcl??????? -->??
???? service? name :orcl??????? -->??
???? 步驟
1? --在二臺機器上都建立oracleNET 即生成listner.ora及tnsnames.ora
--主庫已有listner.ora and tnsnames.ora,需要增加tnsnames.ora到備庫network service names
netmgr
--只需要在備庫上建立(監聽為靜態監聽)和tnsnames
--以上建立完畢，需要主備都啟監聽(注意VBOX可以調界面)
? 1.1 ssh 192.168.1.147---> on primary
????? netmgr
/*1.1?????? cp? -v? $ORACLE_HOME/network/admin/listner.ora $ORACLE_HOME/network/admin/listner.ora.std
?????? cp? -v? $ORACLE_HOME/network/admin/tnsnames.ora $ORACLE_HOME/network/admin/tnsnames.ora.std
????? vi? listner.ora.std
????? vi? tnsnames.ora.std
????? scp listner.ora.std? oracle@192.168.1.57:$ORACLE_HOME/network/admin/listner.ora
????? scp tnsnames.ora.std oracle@192.168.1.57:$ORACLE_HOME/network/admin/tnsnames.ora
????? [oracle@node1 ~]$ cat /u01/app/oracle/product/11.2.0.1/db_1/network/admin/listener.ora
# listener.ora Network Configuration File: /u01/app/oracle/product/11.2.0.1/db_1/network/admin/listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
? (SID_LIST =
??? (SID_DESC =
????? (GLOBAL_DBNAME = orcl)
????? (ORACLE_HOME = /u01/app/oracle/product/11.2.0.1/db_1)
????? (SID_NAME = orcl)
??? )
? )

LISTENER =
? (DESCRIPTION =
??? (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.147)(PORT = 1521))
? )

ADR_BASE_LISTENER = /u01/app/oracle

*/
?????? lsnrctl start? --> on primary,stdby 二邊都要做
?2? --準備備庫的parameter file
??? --on primary
? SQL> show parameter name

NAME???????????????????????????????? TYPE??????? VALUE
------------------------------------ -----------
db_file_name_convert???????????????? string
db_name????????????????????????????? string????? orcl
db_unique_name?????????????????????? string????? orcl
global_names???????????????????????? boolean???? FALSE
instance_name??????????????????????? string????? orcl
lock_name_space????????????????????? string
log_file_name_convert??????????????? string
service_names??????????????????????? string????? orcl
SQL>
SQL> select name from v$controlfile;

NAME
------------------------------------------------------------------------------------------------------------------------
/u01/app/oracle/oradata/orcl/control01.ctl
/u01/app/oracle/flash_recovery_area/orcl/control02.ctl

SQL> select name from v$datafile;

NAME
------------------------------------------------------------------------------------------------------------------------
/u01/app/oracle/oradata/orcl/system01.dbf
/u01/app/oracle/oradata/orcl/sysaux01.dbf
/u01/app/oracle/oradata/orcl/users01.dbf
/u01/app/oracle/oradata/orcl/undotbs1.dbf

7 rows selected.
SQL>

? --add parameter in spfile on primary
SQL> alter system set db_unique_name='orcl' scope=spfile;
SQL> alter system set service_names='orcl' scope=spfile;
SQL> alter system set log_archive_config= 'dg_config=(orcl,orclstd) ' ;
SQL> alter system set log_archive_dest_1=' location =/u01/app/oracle/archivelog/orcl? valid_for=(all_logfiles,all_roles) db_unique_name=orcl' ;
SQL> alter session set log_archive_dest_state_2=defer;
SQL>? alter system set log_archive_dest_2= 'service=to_157 valid_for=( online_logfile,primary_role ) db_unique_name=orclstd';

dg_config?? 注冊成員實例名:oracle_sid

? location ?? 本地相關信息

?service=to_157 輸送到備庫監聽名稱 to_157字符串
--
--??? alter system set log_file_name_convert='remote_archive_path','local_archive_path'
--????????????????????? /home/oracle/archive,/opt/oracle/oradata
--??? alter system set db_file_name_convert='remote_oardata_path','local_oradata_path'
--????????????????????? /home/oracle/oradata,/opt/oracle/oradata

SQL> alter system set? dispatchers='';--在備庫中一定刪除掉
SQL> create pfile='/home/oracle/p.ora' from spfile;

[oracle@node1 ~]$ cp? -v p.ora s.ora
`p.ora' -> `s.ora'
[oracle@node1 ~]$ vim s.ora
[oracle@node1 ~]$ diff? p.ora s.ora
1,9d0
< orcl.__db_cache_size=37748736
< orcl.__java_pool_size=4194304
< orcl.__large_pool_size=4194304
< orcl.__oracle_base='/u01/app/oracle'#ORACLE_BASE set from environment
< orcl.__pga_aggregate_target=117440512
< orcl.__sga_target=218103808
< orcl.__shared_io_pool_size=0
< orcl.__shared_pool_size=130023424
< orcl.__streams_pool_size=4194304
22c13
< *.db_unique_name='orcl'
---
> *.db_unique_name='orclstd'
24d14
< *.dispatchers='(protocol=TCP)'
27,28c17,18
< *.log_archive_dest_1='location=/u01/app/oracle/archivelog/orcl? valid_for=(all_logfiles,all_roles) db_unique_name=orcl'
< *.log_archive_dest_2='service=to_157 valid_for=(online_logfile,primary_role) db_unique_name=orcl02'
?? *.log_arvhice_dest_state_2=defer;
---
> *.log_archive_dest_1='location=/u01/app/oracle/archivelog/orcl? valid_for=(all_logfiles,all_roles) db_unique_name=orclstd'
> *.log_archive_dest_2='service=to_147 valid_for=(online_logfile,primary_role) db_unique_name=orcl'

[oracle@node1 ~]$ scp s.ora oracle@192.168.1.57:/home/oracle
oracle@192.168.1.157's password:
s.ora??????????????????????????????????????????? 100% 1156???? 1.1KB/s?? 00:00???
[oracle@node1 ~]$ scp /u01/app/oracle/product/11.2.0/db_1/dbs/orapworcl oracle@192.168.1.157:/u01/app/oracle/product/11.2.0/db_1/dbs/orapworclstd
oracle@192.168.1.157's password:
orapworcl??????????????????????????????????????? 100% 1536???? 1.5KB/s?? 00:00???
[oracle@node1 ~]$

?

-- on? stdby
[oracle@node2 ~]$ export ORACLE_SID=orcl02
[oracle@node2 ~]$ cat s.oar
--下面照著參數文件進行修改一下
mkdir -pv /u01/app/oracle/admin/orcl/adump
mkdir? -pv /u01/app/oracle/oradata/orcl
mkdir -pv /u01/app/oracle/flash_recovery_area/orcl
mkdir -pv /u01/app/oracle/archivelog/orcl

SQL> startup nomount pfile='/home/oracle/s.ora';
SQL>create spfile from pfile='/home/oracle/s.ora';
--處于NOMOUNT狀態,備庫

[oracle@node2 ~]$ rman target sys/oracle@to_147 auxiliary sys/oracle@to_257

Recovery Manager: Release 11.2.0.1.0 - Production on Thu Mar 8 12:00:44 2012

Copyright (c) 1982, 2009, Oracle and/or its affiliates.? All rights reserved.

connected to target database: ORCL (DBID=1334497743)
connected to auxiliary database: ORCL ( not mounted )
?`
duplicate target database for standby from active database nofilenamecheck;

--duplicate target database for standby from active database nofilenamecheck dorecover ;

--on standby
SQL>alter database open read only--這一步是相當重要的
SQL> alter database open;

SQL> alter database? recover managed standby database disconnect from session;
SQL>
SQL> alter database? recover managed standby database cancel;
SQL> ho lsnrctl stop
SQL> shutdown immeidate;
測試是否歸檔時,數據能夠同步到對面去:
SQL> alter system set log_archive_dest_state_2=enable;?????????????????

System altered.

SQL> alter system switch logfile;

System altered.

SQL> /

System altered.

SQL> /

System altered.

SQL> /

System altered.

關機順序
主庫:
SQL>? alter system set log_archive_dest_state_2=defer;

System altered.

備庫:
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;
注意Data Guard 啟動順序：

?

啟動順序：先standby ,后primary;

閉順序：先primary 后standby;

手工注冊沒有同步的日志,手工COPE過去,這樣才能認得到

alter database register logfile '/home/oracle/archive/1_13_67867676.dbf';
alter database register logfile '/home/oracle/archive/1_14_67867676.dbf';
alter database register logfile '/home/oracle/archive/1_15_67867676.dbf';
select open_mod,protection_mode,database_role from v$database;
select dest_id,error from v$archive_dest where DEST_ID in (1,2);
select sequence#,archvie

?

--最大可用的學習筆記?
SQL>? select database_role from v$database;

DATABASE_ROLE
----------------
PHYSICAL STANDBY
二邊都要做主備庫都要創建為以后切換作準備

SQL> ho mkdir -vp /home/oracle/orcl_stdlog
mkdir: created directory `/home/oracle/orcl_stdlog'

SQL> show parameter standby

NAME???????????????????????????????? TYPE??????? VALUE
------------------------------------ ----------- ------------------------------
standby_archive_dest???????????????? string????? ?/dbs/arch
standby_file_management????????????? string????? MANUAL
SQL> alter database add standby logfile '//home/oracle/orcl_stdlog/stdbylog01.dbf' size .
?

SQL> alter database recover managed standby database cancel;

Database altered.

?

select * from v$standby_log;
SQL>? alter database add standby logfile '/home/oracle/orcl_stdlog/stdbylog01.dbf' size 50m;

Database altered.
--下面修改了SQL后加"/"執行一遍一定要大于在線三組的日志,在這里面建立了四組日志
SQL> c/01/02;
? 1*? alter database add standby logfile '/home/oracle/orcl_stdlog/stdbylog02.dbf' size 50m
SQL> c/02/03
? 1*? alter database add standby logfile '/home/oracle/orcl_stdlog/stdbylog03.dbf' size 50m
SQL> c/03/04
? 1*? alter database add standby logfile '/home/oracle/orcl_stdlog/stdbylog04.dbf' size 50m
SQL>? alter system set standby_file_management=auto;

System altered.

SQL>
SQL> alter system set standby_file_management=auto;--注意二邊都要設置成自動,增加stdbylog之前
手動:
-----------------
主庫:

?

alter system set log_archive_dest_1='location=/home/oracle/log_archive lgwr affirm sync valid_for=(all_logfiles,all_roles) db_unique_name=orcl';
alter system set log_archive_dest_2='service=to_157? lgwr affirm sync valid_for=(online_logfile,primary_role) db_unique_name=orcl02';
alter system set log_archive_dest_3='location=/home/oracle/standbylog_archive valid_for=(standby_logfile,standby_role) db_unique_name=orcl';
ho mkdir -pv /home/oracle/standbylog_archive;

?

ho mkdir -pv /home/oracle/standbylog_archive;
standby--備庫,為未來做切換做好準備
主庫假設就是切換成備庫
ho mkdir -pv /home/oracle/standbylog_archive;
alter system set log_archive_dest_1='location=/home/oracle/log_archive lgwr affirm sync valid_for=(all_logfiles,all_roles) db_unique_name=orcl02';
alter system set log_archive_dest_2='service=to_147? lgwr affirm sync valid_for=(online_logfle,primary_role) db_unique_name=orcl';
alter system set log_archive_dest_3='location=/home/oracle/standbylog_archive valid_for=(standby_logfile,standby_role) db_unique_name=orcl02';
ho mkdir -pv /home/oracle/standbylog_archive;

?

查詢是否已經應用:
select sequence#,applied,archived from v$archived_log;

show parameter log_archive_dest
備庫:
--準備這一次在創建好,實時應用日志
alter database recover managed standby database using current logfile disconnect? from session
主庫:

select protection_mode from v$database;
SQL> alter system set log_archive_dest_state_2=enable;

System altered.

SQL> select SWITCHOVER_STATUS from v$database;

SWITCHOVER_STATUS
--------------------
TO STANDBY

alter database set standby database to maximize availability;

查詢自己創建了多少組備庫的日志組
SQL> select * from v$standby_log;

?select group#,dbid,thread#,sequence# from? v$standby_log;

SQL> select status from v$instance;

STATUS
------------
OPEN

SQL> select open_mode from v$database;

OPEN_MODE
--------------------
select protection_mode,database_role,protection_level from v$database;

主庫主動關閉
SQL> select SWITCHOVER_STATUS from v$database;

SWITCHOVER_STATUS
--------------------
TO STANDBY

SQL> alter system switch logfile;

System altered.

SQL> /

Database altered.

?

?

select open_mode from v$database;

?

select dest_id,status,destination,error from v$archive_dest where dest_id<=5;

SELECT NAME FROM V$ARCHIVED_LOG WHERE THREAD#=1 AND DEST_ID=1
AND SEQUENCE# BETWEEN 50 AND 202;

----------切換主備?? 切換之前前再一TNSPING 網絡?? 切換之后記得改ENABLE? 新主庫alter system set log_archive_dest_state_2=enable;

主庫
在最大可用的物理standby要擁有自己的聯機日志:接收主庫傳送過來的redo條目
alter database add standby logfile '' size 50m;
alter database add standby logfile '' size 50m;
alter database add standby logfile '' size 50m;
alter database add standby logfile '' size 50m;
SQL>? alter system set standby_file_management=auto;
SQL> alter database set standby database to maximize availability;

Database altered.

?

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
TO STANDBY

SQL> alter database commit to switchover to physical standby;

Database altered.

?

SQL> select status from v$instance;

STATUS
------------
STARTED

SQL> shutdown abort;
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area? 931143680 bytes
Fixed Size????????????????? 2218872 bytes
Variable Size???????????? 578815112 bytes
Database Buffers????????? 343932928 bytes
Redo Buffers??????????????? 6176768 bytes
Database mounted.
Database opened.
SQL> alter database recover managed standby database using current logfile disconnect? from session;

Database altered.

SQL> alter system set standby_file_management=auto;

System altered.

SQL> select protection_mode,database_role,protection_level from v$database;

PROTECTION_MODE????? DATABASE_ROLE??? PROTECTION_LEVEL
-------------------- ---------------- --------------------
MAXIMUM AVAILABILITY PHYSICAL STANDBY RESYNCHRONIZATION

SQL>

備庫SQL>? select PROTECTION_MODE from v$database;

PROTECTION_MODE
--------------------
MAXIMUM AVAILABILITY

SQL> alter system set log_archive_dest_state_2=enable;

System altered.

SQL>? select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
NOT ALLOWED

SQL> alter database commit to switchover to primary;

Database altered.

SQL>? alter system set log_archive_dest_state_2=enable;--理解這二個地方的意思

System altered.

SQL> alter system set standby_file_management=auto;--理解這二個地方的意思,切換時會報錯

System altered.

SQL> select open_mode from v$database;

OPEN_MODE
--------------------
MOUNTED

SQL> alter database open;

Database altered.

SQL> select protection_mode,database_role,protection_level from v$database;

PROTECTION_MODE????? DATABASE_ROLE??? PROTECTION_LEVEL
-------------------- ---------------- --------------------
MAXIMUM AVAILABILITY PRIMARY????????? RESYNCHRONIZATION
實踐體現:
1、oracle數據庫每天凌晨4：00：00會對現網的adway的數據做一個exp導出整個用戶的操作，在現網數據有問題時，可以恢復到前一天的凌晨4點的狀態。
? 需要整個數據庫至昨天的狀態步驟如下：
? SQL> drop user zboss_user;
? SQL> create user zboss_user identified by izptec;
? SQL> grant connect,resource to zboss_user;
? cd /home/oracle/backdm/
? imp zboss_user/izptec file=./zboss1_date_2010-12-20.dmp full=y
? 需要恢復表table1、table2至昨天的狀態
? cd /home/oracle/backdm/
? 進入數據庫把兩張表清空，
? imp zboss_user/izptec file=./zboss1_date_2010-12-20.dmp tables=table1，table2
2、oracle在武漢111.175.242.22服務器上做了dataguard，對現網數據庫進行實時同步，若現網數據庫down機了，恢復只需要15分鐘?
?? 主庫需要做的操作
? Dataguard 角色切換（由PRIMARY DB到STANDBY DB）
? 首先應把primary db切換成standby db（如果主庫已經down掉了，就不用做這一步了）
? SQL>alter? database commit to switchover to physical standby with session shutdown;
? SQL>shutdown immediate;
? SQL>startup mount;
? SQL>alter database recover managed standby database disconnect from session;
? 查看狀態
? SQL>select name,database_role from v$database;
? NAME????? DB_UNIQUE_NAME???????????????? PROTECTION_MODE
? --------- ------------------------------ --------------------
? STANDBY?? STANDBY??????????????????????? UNPROTECTED
? 看到主庫已經成了備庫.
? 備庫需要做的操作
? 接著把standby db 切換成primary db
? SQL> alter database commit to switchover to primary;
? SQL> shutdown immediate;
? SQL> startup;
? 查看狀態
? SQL> select name,database_role from v$database;
? NAME????? DATABASE_ROLE
? --------- ----------------
? STANDBY?? PRIMARY
? 從primary關鍵字可以看出備庫切換成了主庫.
? 這樣就恢復到主庫down機前的狀態了。
===========================================主庫一輪切換======================
? datafile 3 switched to datafile copy
input datafile copy RECID=5 STAMP=825206190 file name=/u01/app/oracle/oradata/orcl/undotbs01.dbf
datafile 4 switched to datafile copy
input datafile copy RECID=6 STAMP=825206190 file name=/u01/app/oracle/oradata/orcl/users01.dbf

contents of Memory Script:
{
?? set until scn? 1050293;
?? recover
?? standby
?? clone database
??? delete archivelog
?? ;
}
executing Memory Script

executing command: SET until clause

Starting recover at 04-SEP-13
using channel ORA_AUX_DISK_1

starting media recovery

archived log for thread 1 with sequence 2 is already on disk as file /u01/app/oracle/product/11.2.0.1/db_1/dbs/arch1_2_825206525.dbf
archived log file name=/u01/app/oracle/product/11.2.0.1/db_1/dbs/arch1_2_825206525.dbf thread=1 sequence=2
media recovery complete, elapsed time: 00:00:01
Finished recover at 04-SEP-13
Finished Duplicate Db at 04-SEP-13

RMAN> exit

Recovery Manager complete.
[oracle@node1 ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.1.0 Production on Wed Sep 4 00:14:14 2013

Copyright (c) 1982, 2009, Oracle.? All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL>? select group#,dbid,thread# from v$standby_log;

??? GROUP# DBID??????????????????????????????????????? THREAD#
---------- ---------------------------------------- ----------
???????? 4 UNASSIGNED??????????????????????????????????????? 1
???????? 5 UNASSIGNED??????????????????????????????????????? 1
???????? 6 UNASSIGNED??????????????????????????????????????? 0
???????? 7 UNASSIGNED??????????????????????????????????????? 0

SQL> ho /home/oracle/standby_log_archive;
/bin/bash: /home/oracle/standby_log_archive: No such file or directory

SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[oracle@node1 ~]$ ls /home/oracle/standbylog_archive
1_19_825119295.dbf? 1_21_825119295.dbf
1_20_825119295.dbf? o1_mf_2_92ct2t1v_.log
[oracle@node1 ~]$ ls /home/oracle/standbylog_archive -l
total 62844
-rw-r----- 1 oracle oinstall???? 1024 Sep? 3 22:56 1_19_825119295.dbf
-rw-r----- 1 oracle oinstall? 9760256 Sep? 3 22:57 1_20_825119295.dbf
-rw-r----- 1 oracle oinstall? 2073088 Sep? 3 23:01 1_21_825119295.dbf
-rw-r----- 1 oracle oinstall 52429312 Sep? 3 23:25 o1_mf_2_92ct2t1v_.log
[oracle@node1 ~]$ ls -l? /home/oracle/standbylog_archive
total 62844
-rw-r----- 1 oracle oinstall???? 1024 Sep? 3 22:56 1_19_825119295.dbf
-rw-r----- 1 oracle oinstall? 9760256 Sep? 3 22:57 1_20_825119295.dbf
-rw-r----- 1 oracle oinstall? 2073088 Sep? 3 23:01 1_21_825119295.dbf
-rw-r----- 1 oracle oinstall 52429312 Sep? 3 23:25 o1_mf_2_92ct2t1v_.log
[oracle@node1 ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.1.0 Production on Wed Sep 4 00:22:42 2013

Copyright (c) 1982, 2009, Oracle.? All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> archive log list;
Database log mode????????????? Archive Mode
Automatic archival???????????? Enabled
Archive destination??????????? /home/oracle/standbylog_archive
Oldest online log sequence???? 4
Next log sequence to archive?? 6
Current log sequence?????????? 6
SQL> alter system set log_archive_dest_3='location=/home/oracle/standbylog_archive valid_for=(standby_logfile,standby_role) db_unique_name=orcl';

System altered.

SQL> alter system set standby_file_management=auto;

System altered.

SQL> alter system set log_archive_dest_state_2=enable;

System altered.

SQL> ho tnsping to_157;

TNS Ping Utility for Linux: Version 11.2.0.1.0 - Production on 04-SEP-2013 00:33:46

Copyright (c) 1997, 2009, Oracle.? All rights reserved.

Used parameter files:
/u01/app/oracle/product/11.2.0.1/db_1/network/admin/sqlnet.ora

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.157)(PORT = 1521))) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl)))
OK (20 msec)

SQL> create table scott.yun as select * from dba_tables;

Table created.

SQL> select protection_mode from v$database;

PROTECTION_MODE
--------------------
MAXIMUM AVAILABILITY

SQL> select sequence#,applied,archived from v$archived_log;

?SEQUENCE# APPLIED?? ARC
---------- --------- ---
???????? 7 YES?????? YES
???????? 8 YES?????? YES
???????? 9 YES?????? YES
??????? 10 YES?????? YES
??????? 10 YES?????? YES
??????? 11 YES?????? YES
??????? 11 YES?????? YES
??????? 12 YES?????? YES
??????? 12 YES?????? YES
??????? 13 YES?????? YES
??????? 13 YES?????? YES

?SEQUENCE# APPLIED?? ARC
---------- --------- ---
??????? 14 YES?????? YES
??????? 14 YES?????? YES
??????? 15 YES?????? YES
??????? 15 YES?????? YES
??????? 16 YES?????? YES
??????? 16 YES?????? YES
??????? 17 YES?????? YES
??????? 17 YES?????? YES
??????? 18 YES?????? YES
??????? 18 YES?????? YES
??????? 19 YES?????? YES

?SEQUENCE# APPLIED?? ARC
---------- --------- ---
??????? 19 YES?????? YES
??????? 20 NO??????? YES
??????? 20 YES?????? YES
??????? 21 NO??????? YES
??????? 21 YES?????? YES
???????? 1 NO??????? YES
???????? 2 NO??????? YES
???????? 3 NO??????? YES
???????? 3 YES?????? YES
???????? 4 NO??????? YES
???????? 4 YES?????? YES

?SEQUENCE# APPLIED?? ARC
---------- --------- ---
???????? 5 NO??????? YES
???????? 5 YES?????? YES
???????? 6 NO??????? YES
???????? 6 YES?????? YES
???????? 7 NO??????? YES
???????? 7 NO??????? YES

39 rows selected.

SQL> ho ls -l /home/oracle/standbylog_archive;
total 62844
-rw-r----- 1 oracle oinstall???? 1024 Sep? 3 22:56 1_19_825119295.dbf
-rw-r----- 1 oracle oinstall? 9760256 Sep? 3 22:57 1_20_825119295.dbf
-rw-r----- 1 oracle oinstall? 2073088 Sep? 3 23:01 1_21_825119295.dbf
-rw-r----- 1 oracle oinstall 52429312 Sep? 3 23:25 o1_mf_2_92ct2t1v_.log

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
TO STANDBY

SQL> alter database commit to switchover to physical standby;?

Database altered.

SQL> shutdown immediate;
ORA-01507: database not mounted

ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.

Total System Global Area? 931143680 bytes
Fixed Size????????????????? 2218872 bytes
Variable Size???????????? 578815112 bytes
Database Buffers????????? 343932928 bytes
Redo Buffers??????????????? 6176768 bytes
Database mounted.
SQL> alter database recover managed standby database using current logfile disconnect from session;

Database altered.

SQL> select name,database_role from v$database;

NAME????? DATABASE_ROLE
--------- ----------------
ORCL????? PHYSICAL STANDBY

SQL> alter system set standby_file_management=auto;

System altered.

SQL>? alter system set log_archive_dest_state_2=enable;

System altered.
--一般備庫下的狀態為NOT ALLOWED是不能切換的,因為一山不容二虎,第一先把主庫降下來后,才能把主庫提上去,提之前,新備庫得進恢復模式,新主庫得DEST_STATE_2再次重置enable
SQL> select SWITCHOVER_STATUS from v$database;

SWITCHOVER_STATUS
--------------------
NOT ALLOWED

SQL> ho tnsping to_157

TNS Ping Utility for Linux: Version 11.2.0.1.0 - Production on 04-SEP-2013 00:46:36

Copyright (c) 1997, 2009, Oracle.? All rights reserved.

Used parameter files:
/u01/app/oracle/product/11.2.0.1/db_1/network/admin/sqlnet.ora

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.157)(PORT = 1521))) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl)))
OK (0 msec)

SQL> select SWITCHOVER_STATUS from v$database;

SWITCHOVER_STATUS
--------------------
NOT ALLOWED

SQL> select open_mode from v$database;

OPEN_MODE
--------------------
MOUNTED
--在恢復模式下不能開庫,得取消恢復狀態
SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-10456: cannot open standby database; media recovery session may be in
progress

SQL>? alter database recover managed standby database cancel;

Database altered.

SQL> alter database open;

Database altered.

SQL> alter database recover managed standby database using current logfile disconnect from session;

Database altered.

SQL> select count(*) from scott.cwm;

? COUNT(*)
----------
????? 2730

SQL>? ho tnsping to_157

TNS Ping Utility for Linux: Version 11.2.0.1.0 - Production on 04-SEP-2013 00:51:28

Copyright (c) 1997, 2009, Oracle.? All rights reserved.

Used parameter files:
/u01/app/oracle/product/11.2.0.1/db_1/network/admin/sqlnet.ora

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.157)(PORT = 1521))) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl)))
OK (10 msec)

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
NOT ALLOWED

SQL> alter database commit to switchover to primary;

Database altered.

SQL> alter system set log_archive_dest_state_2=enable;

System altered.

SQL>? alter system set standby_file_management=auto;

System altered.

SQL> alter system set log_archive_dest_state_2=enable;

System altered.
--由于第二輪切換時的新主庫還未處于OPEN狀態下面
SQL> create table scott.chenjian as select * from dba_objects;
create table scott.chenjian as select * from dba_objects
*
ERROR at line 1:
ORA-01109: database not open

SQL> alter database open;

Database altered.

SQL> alter system set log_archive_dest_state_2=enable;

System altered.

SQL> create table scott.chenjian as select * from dba_objects;

Table created.

?

SQL> show parameter date

NAME???????????????????????????????? TYPE??????? VALUE
------------------------------------ ----------- ------------------------------
fixed_date?????????????????????????? string
nls_date_format????????????????????? string
nls_date_language??????????????????? string

SQL> alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';

Session altered.

SQL>? select sysdate from dual;

SYSDATE
-------------------
2013-09-04 01:05:55

SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[oracle@node1 ~]$ exit
logout
[root@node1 ~]# ifconfig
eth0????? Link encap:Ethernet? HWaddr 08:00:27:9C:CC:51?
????????? inet addr:192.168.56.147? Bcast:192.168.56.255? Mask:255.255.255.0
????????? inet6 addr: fe80::a00:27ff:fe9c:cc51/64 Scope:Link
????????? UP BROADCAST RUNNING MULTICAST? MTU:1500? Metric:1
????????? RX packets:750606 errors:0 dropped:0 overruns:0 frame:0
????????? TX packets:132742 errors:0 dropped:0 overruns:0 carrier:0
????????? collisions:0 txqueuelen:0
????????? RX bytes:179921301 (171.5 MiB)? TX bytes:2845074889 (2.6 GiB)

eth0:1??? Link encap:Ethernet? HWaddr 08:00:27:9C:CC:51?
????????? inet addr:192.168.1.147? Bcast:192.168.1.255? Mask:255.255.255.0
????????? UP BROADCAST RUNNING MULTICAST? MTU:1500? Metric:1

?

[root@node1 ~]# su - oracle
[oracle@node1 ~]$ cat /u01/app/oracle/product/11.2.0.1/db_1/network/admin/listener.ora
# listener.ora Network Configuration File: /u01/app/oracle/product/11.2.0.1/db_1/network/admin/listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
? (SID_LIST =
??? (SID_DESC =
????? (GLOBAL_DBNAME = orcl)
????? (ORACLE_HOME = /u01/app/oracle/product/11.2.0.1/db_1)
????? (SID_NAME = orcl)
??? )
? )

LISTENER =
? (DESCRIPTION =
??? (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.147)(PORT = 1521))
? )

ADR_BASE_LISTENER = /u01/app/oracle
===========================備庫=192.168.56.157==========================================================

??? GROUP# DBID??????????????????????????????????????? THREAD#
---------- ---------------------------------------- ----------
???????? 4 1352900027??????????????????????????????????????? 1
???????? 5 1352900027??????????????????????????????????????? 1
???????? 6 1352900027??????????????????????????????????????? 1
???????? 7 UNASSIGNED??????????????????????????????????????? 0

SQL> ho ls /home/oracle/standbylog_archive
1_14_825119295.dbf? 1_15_825119295.dbf? 1_16_825119295.dbf? 1_17_825119295.dbf? 1_18_825119295.dbf

SQL> ho ls /home/oracle/ -l
total 2297868
drwxr-xr-x 8 oracle oinstall?????? 4096 Aug 21? 2009 database
-rw-r--r-- 1 root?? root???? 1239269270 Dec? 1? 2012 linux.x64_11gR2_database_1of2.zip
-rw-r--r-- 1 root?? root???? 1111416131 Dec? 1? 2012 linux.x64_11gR2_database_2of2.zip
drwxrwxr-x 2 oracle oinstall?????? 4096 Sep? 3 23:01 log_archive
drwxr-xr-x 3 oracle oinstall?????? 4096 Sep? 1 10:10 oradiag_oracle
drwxr-xr-x 2 oracle oinstall?????? 4096 Sep? 3 22:09 orcl_stdlog
-rw-r--r-- 1 oracle oinstall??????? 845 Sep? 3 21:20 s.ora
drwxr-xr-x 2 oracle oinstall?????? 4096 Sep? 3 22:32 standbylog_archive

SQL> ho ls -l? /home/oracle/standbylog_archive
total 2660
-rw-r----- 1 oracle oinstall? 858624 Sep? 3 22:14 1_14_825119295.dbf
-rw-r----- 1 oracle oinstall 1043968 Sep? 3 22:18 1_15_825119295.dbf
-rw-r----- 1 oracle oinstall? 786432 Sep? 3 22:32 1_16_825119295.dbf
-rw-r----- 1 oracle oinstall??? 1536 Sep? 3 22:32 1_17_825119295.dbf
-rw-r----- 1 oracle oinstall?? 13312 Sep? 3 22:32 1_18_825119295.dbf

SQL> alter system set standby_file_management=auto
? 2? ;

System altered.

SQL> alter system set log_archive_dest_1='location=/home/oracle/log_archive lgwr affirm sync valid_for=(all_logfiles,all_roles) db_unique_name=orcl02';

System altered.

SQL> alter system set log_archive_dest_2='service=to_147? lgwr affirm sync valid_for=(online_logfile,primary_role) db_unique_name=orcl';

System altered.

SQL> ho mkdir -pv /home/oracle/standbylog_archive;

SQL> alter system set log_archive_dest_3='location=/home/oracle/standbylog_archive valid_for=(standby_logfile,standby_role) db_unique_name=orcl02';

System altered.

SQL> alter system set standby_file_management=auto;

System altered.

SQL> alter database recover managed standby database using current logfile disconnect? from session
? 2? ;

Database altered.

?

SQL> alter database recover managed standby database cancel;

Database altered.

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area? 931143680 bytes
Fixed Size????????????????? 2218872 bytes
Variable Size???????????? 545260680 bytes
Database Buffers????????? 377487360 bytes
Redo Buffers??????????????? 6176768 bytes
Database mounted.
raDatabase opened.
SQL> show parameter archive
SP2-0734: unknown command beginning "rashow par..." - rest of line ignored.
SQL> show parameter log_archive_dest

NAME???????????????????????????????? TYPE??????? VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest???????????????????? string
log_archive_dest_1?????????????????? string????? location=/home/oracle/log_arch
???????????????????????????????????????????????? ive valid_for=(all_logfiles,al
???????????????????????????????????????????????? l_roles) db_unique_name=orcl
log_archive_dest_10????????????????? string
log_archive_dest_11????????????????? string
log_archive_dest_12????????????????? string
log_archive_dest_13????????????????? string
log_archive_dest_14????????????????? string
log_archive_dest_15????????????????? string
log_archive_dest_16????????????????? string

NAME???????????????????????????????? TYPE??????? VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_17????????????????? string
log_archive_dest_18????????????????? string
log_archive_dest_19????????????????? string
log_archive_dest_2?????????????????? string????? service=to_157 valid_for=(onli
???????????????????????????????????????????????? ne_logfile,primary_role) db_un
???????????????????????????????????????????????? ique_name=orcl02
log_archive_dest_20????????????????? string
log_archive_dest_21????????????????? string
log_archive_dest_22????????????????? string
log_archive_dest_23????????????????? string
log_archive_dest_24????????????????? string

NAME???????????????????????????????? TYPE??????? VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_25????????????????? string
log_archive_dest_26????????????????? string
log_archive_dest_27????????????????? string
log_archive_dest_28????????????????? string
log_archive_dest_29????????????????? string
log_archive_dest_3?????????????????? string
log_archive_dest_30????????????????? string
log_archive_dest_31????????????????? string
log_archive_dest_4?????????????????? string
log_archive_dest_5?????????????????? string
log_archive_dest_6?????????????????? string

NAME???????????????????????????????? TYPE??????? VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_7?????????????????? string
log_archive_dest_8?????????????????? string
log_archive_dest_9?????????????????? string
log_archive_dest_state_1???????????? string????? enable
log_archive_dest_state_10??????????? string????? enable
log_archive_dest_state_11??????????? string????? enable
log_archive_dest_state_12??????????? string????? enable
log_archive_dest_state_13??????????? string????? enable
log_archive_dest_state_14??????????? string????? enable
log_archive_dest_state_15??????????? string????? enable
log_archive_dest_state_16??????????? string????? enable

NAME???????????????????????????????? TYPE??????? VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_state_17??????????? string????? enable
log_archive_dest_state_18??????????? string????? enable
log_archive_dest_state_19??????????? string????? enable
log_archive_dest_state_2???????????? string????? enable
log_archive_dest_state_20??????????? string????? enable
log_archive_dest_state_21??????????? string????? enable
log_archive_dest_state_22??????????? string????? enable
log_archive_dest_state_23??????????? string????? enable
log_archive_dest_state_24??????????? string????? enable
log_archive_dest_state_25??????????? string????? enable
log_archive_dest_state_26??????????? string????? enable

NAME???????????????????????????????? TYPE??????? VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_state_27??????????? string????? enable
log_archive_dest_state_28??????????? string????? enable
log_archive_dest_state_29??????????? string????? enable
log_archive_dest_state_3???????????? string????? enable
log_archive_dest_state_30??????????? string????? enable
log_archive_dest_state_31??????????? string????? enable
log_archive_dest_state_4???????????? string????? enable
log_archive_dest_state_5???????????? string????? enable
log_archive_dest_state_6???????????? string????? enable
log_archive_dest_state_7???????????? string????? enable
log_archive_dest_state_8???????????? string????? enable

NAME???????????????????????????????? TYPE??????? VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_state_9???????????? string????? enable
SQL> select group#,dbid,thread#,sequence# from? v$standby_log;

??? GROUP# DBID??????????????????????????????????????? THREAD#? SEQUENCE#
---------- ---------------------------------------- ---------- ----------
???????? 4 1352900027??????????????????????????????????????? 1????????? 4
???????? 5 1352900027??????????????????????????????????????? 1????????? 3
???????? 6 1352900027??????????????????????????????????????? 1????????? 5
???????? 7 UNASSIGNED??????????????????????????????????????? 0????????? 0

SQL> alter system set log_archive_dest_1='location=/home/oracle/log_archive lgwr affirm sync valid_for=(all_logfiles,all_roles) db_unique_name=orcl02';

System altered.

SQL> alter system set log_archive_dest_2='service=to_147? lgwr affirm sync valid_for=(online_logfile,primary_role) db_unique_name=orcl';

System altered.

SQL> alter system set log_archive_dest_3='location=/home/oracle/standbylog_archive valid_for=(standby_logfile,standby_role) db_unique_name=orcl02';

System altered.

?

SQL> alter database recover managed standby database using current logfile disconnect from session;

Database altered.

SQL>? ho tnsping to_147

TNS Ping Utility for Linux: Version 11.2.0.1.0 - Production on 04-SEP-2013 00:19:02

Copyright (c) 1997, 2009, Oracle.? All rights reserved.

Used parameter files:
/u01/app/oracle/product/11.2.0.1/db_1/network/admin/sqlnet.ora

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.147)(PORT = 1521))) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl)))
OK (60 msec)

SQL> select count(*) from scott.yun;

? COUNT(*)
----------
????? 2728

SQL>
select protection_mode from v$database;SQL>

PROTECTION_MODE
--------------------
MAXIMUM AVAILABILITY

SQL> select sequence#,applied,archived from v$archived_log;

?SEQUENCE# APPLIED?? ARC
---------- --------- ---
???????? 2 YES?????? YES
???????? 3 YES?????? YES
???????? 4 YES?????? YES
???????? 5 YES?????? YES
???????? 6 YES?????? YES
???????? 7 NO??????? YES
???????? 7 IN-MEMORY YES

7 rows selected.

SQL> ho ls -l /home/oracle/standbylog_archive;
total 2696
-rw-r----- 1 oracle oinstall? 858624 Sep? 3 22:14 1_14_825119295.dbf
-rw-r----- 1 oracle oinstall 1043968 Sep? 3 22:18 1_15_825119295.dbf
-rw-r----- 1 oracle oinstall? 786432 Sep? 3 22:32 1_16_825119295.dbf
-rw-r----- 1 oracle oinstall??? 1536 Sep? 3 22:32 1_17_825119295.dbf
-rw-r----- 1 oracle oinstall?? 13312 Sep? 3 22:32 1_18_825119295.dbf
-rw-r----- 1 oracle oinstall?? 34816 Sep? 4 00:16 1_7_825206525.dbf

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
NOT ALLOWED

SQL> /??????????????????????

SWITCHOVER_STATUS
--------------------
TO PRIMARY
--備庫切成新主庫后,記得一定要先一致性關閉數據,直接啟動數據庫之前,新備庫一定到恢復模式下,然后才能在新主庫上面執行
--alter system set log_archive_dest_state_2=enable;

--切到主庫,如果有SESSION,就在后面加上 with session shutdown;
SQL> alter database commit to switchover to primary;

Database altered.

SQL> shutdown immediate;
ORA-01109: database not open

Database dismounted.
ORACLE instance shut down.
SQL> startup;
ORACLE instance started.

Total System Global Area? 931143680 bytes
Fixed Size????????????????? 2218872 bytes
Variable Size???????????? 545260680 bytes
Database Buffers????????? 377487360 bytes
Redo Buffers??????????????? 6176768 bytes
Database mounted.
Database opened.
SQL> select name ,database_role from v$database;

NAME????? DATABASE_ROLE
--------- ----------------
ORCL????? PRIMARY

SQL> alter system set standby_file_management=auto;

System altered.

SQL> alter system set log_archive_dest_state_2=enable;

System altered.
--新主庫注意是在157上面的舊備庫
SQL> select SWITCHOVER_STATUS from v$database;

SWITCHOVER_STATUS
--------------------
TO STANDBY

SQL> ho tnsping to_147

TNS Ping Utility for Linux: Version 11.2.0.1.0 - Production on 04-SEP-2013 00:31:30

Copyright (c) 1997, 2009, Oracle.? All rights reserved.

Used parameter files:
/u01/app/oracle/product/11.2.0.1/db_1/network/admin/sqlnet.ora

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.147)(PORT = 1521))) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl)))
OK (10 msec)

SQL>? alter system set log_archive_dest_state_2=enable;

System altered.

SQL> create table scott.cl as select * from dba_objects;

Table created.

SQL>? alter system set log_archive_dest_state_2=enable;

System altered.
--新主庫創建一張表,驗證是否無縫同步到備庫里面去
SQL> create table scott.cwm as select * from dba_tables;

Table created.

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
TO STANDBY
--在正常切換之前一定要記得查詢監聽,這是在計劃下切換數據庫
SQL> ho tnsping to_157

TNS Ping Utility for Linux: Version 11.2.0.1.0 - Production on 04-SEP-2013 00:36:22

Copyright (c) 1997, 2009, Oracle.? All rights reserved.

Used parameter files:
/u01/app/oracle/product/11.2.0.1/db_1/network/admin/sqlnet.ora

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.157)(PORT = 1521))) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl)))
OK (10 msec)

SQL>? ho tnsping to_147

TNS Ping Utility for Linux: Version 11.2.0.1.0 - Production on 04-SEP-2013 00:36:38

Copyright (c) 1997, 2009, Oracle.? All rights reserved.

Used parameter files:
/u01/app/oracle/product/11.2.0.1/db_1/network/admin/sqlnet.ora

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.147)(PORT = 1521))) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl)))
OK (10 msec)

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
TO STANDBY
--原備庫成新主加,現在準備切換為物理庫
SQL> alter database commit to switchover to physical standby;?????????????

Database altered.

SQL> shutdown immediate;
ORA-01507: database not mounted

ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.

Total System Global Area? 931143680 bytes
Fixed Size????????????????? 2218872 bytes
Variable Size???????????? 545260680 bytes
Database Buffers????????? 377487360 bytes
Redo Buffers??????????????? 6176768 bytes
Database mounted.
SQL> alter database recover managed standby database disconnect from session;

Database altered.

SQL> alter database recover managed standby database cancel;

Database altered.

?

?

SQL> alter database recover managed standby database using current logfile disconnect from session;

Database altered.

SQL>? alter system set standby_file_management=auto;

System altered.

SQL> alter system set log_archive_dest_state_2=enable;

System altered.

SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-10456: cannot open standby database; media recovery session may be in
progress

SQL> select status from v$instance;

STATUS
------------
MOUNTED

SQL>? alter database recover managed standby database cancel; --退出恢復模式才能開庫,因為以前的都只能在MOUNT狀態下,現在可以READ ONLY

Database altered.

SQL> alter database open;

Database altered.

SQL> alter database recover managed standby database using current logfile disconnect from session;

Database altered.

SQL> select count(*) from scott.chenjian;

? COUNT(*)
----------
???? 71904

SQL> alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';

Session altered.

SQL>? select sysdate from dual;

SYSDATE
-------------------
2013-09-04 00:51:17

?

搭建實時同步data guard的最高可用-切換主備