通过RMAN DUPLICATE...FROM ACTIVE DATABASE创建dataguard(for oracle 11g)
oracle 10g可以通过基于备份的rman DUPLICATE实现dataguard，通过步骤需要对
数据库进行备份，并在standby侧进行数据库的恢复。而到了11g，oracle推出了Duplicate From Active Database技术，不需要再对数据库进行rman备份恢复，一切动作都通过网络自动完成。
下面是具体的实现例子：
primary db：hrdbprim
standby db:standby(由于是三个节点的rac，实例名为standby1）
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一、primary侧的环境准备：
1，确保数据库归档状态
[sql]
SQL> select log_mode from v$database;
LOG_MODE
------------
ARCHIVELOG
2，Enable force logging
[sql]
SQL> ALTER DATABASE FORCE LOGGING;
Database altered.
3，生成standby redolog
[sql]
SQL> alter database add standby logfile '/oracle/app/oracle/oradata/hrdbprim/redo11.log' size 50m;
Database altered.
4，修改primary参数文件spfile，需要设置以下8个参数
[sql]
SQL> alter system set LOG_ARCHIVE_CONFIG='DG_CONFIG=(hrdbprim,standby)';
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System altered.
SQL> alter system set LOG_ARCHIVE_DEST_1='LOCATION=/oracle/app/oracle/oradata/hrdbprim/ VALID_FOR=(ALL_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=hrdbprim';
System altered.
SQL> alter system set LOG_ARCHIVE_DEST_2='SERVICE=standby LGWR ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=standby';
System altered.
SQL> alter system set LOG_ARCHIVE_DEST_STATE_1=ENABLE;
System altered.
SQL> alter system set FAL_SERVER=standby;
System altered.
SQL> alter system set FAL_CLIENT=standby;
System altered.
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SQL> alter system set DB_FILE_NAME_CONVERT='/oracle/app/oracle/oradata/hrdbprim/','+DATA/standby/datafile/' scope=spfile;
System altered.
SQL> alter system set LOG_FILE_NAME_CONVERT='/oracle/app/oracle/oradata/hrdbprim/','+DATA/standby/onlinelog/' scope=spfile;
System altered.
二、修改sql*net相关文件，确保网络环境准备,确保互相tnsping通
listener.ora
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME = standby)
(ORACLE_HOME = /oracle/app/oracle/product/11.2.0/db_1)
(SID_NAME = standby3)
)
)
LISTENER =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.4.124.235)(PORT = 1521))
)
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tnsnames.ora
hrdbprim =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.4.124.239)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = hrdbprim)
)
)
standby =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.4.124.235)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = standby)(UR=A)
)
)
三、创建standby数据库
1，password密码文件；既可以从primary复制改名，也可以重新生成一个，主要要保持sys口令一致，这里采用复制方式
sftp ...
mv orapwhrdbprim orapwstandby
2,新建pfile文件，注意pfile要放在$ORACLE_HOME/dbs目录,否则启动时需要指定pfile文件,注意启动时必须使用pfile文件启动，否者无法复制
vi initstandby3.ora
DB_NAME=standby
DB_UNIQUE_NAME=standby
*.audit_file_dest='/oracle/app/oracle/admin/standby/adump'
*.control_files='+DATA/standby/controlfile/control01.ctl','+FRA/standby/controlfile/control02.ctl'
*.db_create_file_dest='+DATA'
*.db_block_size=8192
*.db_recovery_file_dest='+FRA'
*.db_recovery_file_dest_size=10