DataGuard是甲骨文推出的一种高可用性数据库方案，在Oracle 8i之前被称为Standby Database。从Oracle 9i开始，正式更名为Data Guard。它是在主节点与备用节点间通过日志同步来保证数据的同步，可以实现数据库快速切换与灾难性恢复。Data Guard只是在软件上对数据库进行设置，并不需要额外购买任何组件。用户能够在对主数据库影响很小的情况下，实现主备数据库的同步。而主备机之间的数据差异只限于在线日志部分，因此被不少企业用作数据容灾解决方案。（以上是度娘解释，本人理解 dataguard设计之初为异地容灾，他的应急切换能提供很好的高可用，但同时对外服务还是只有一台pridb，所以性能未有所提高）此次配置为dataguard物理备库最大性能模式。
1）linux操作系统安装并安装oracle10g软件
ps：主库安装数据库软件并建库，备库只需要安装oracle软件不需要建库
以下主库简称pridb备库stydb
本次环境：
pridb 172.25.56.149
stydb 172.25.56.150
2）pridb配置
1.查看是否开启归档模式（由于dataguard高性能需要运用到archivelog恢复stydb，所以必须开启）
archive log list
如果没有开启 需将数据库打至mount模式后开启
alter database archivelog;
alter database force logging;（开启强制归档，有时候由于语句not logging 可能未生成redolog）
生成standby controlfile
alter database create standby controlfile as '/u01/temp/standbycontrolfile.ctl';
2.查询pridb如下文件位置
datafile （select name from v$datafile;）
redologfile （select member from v$logfile;）
controlfile （show parameter control_files）
spfile （show parameter spfile）
3.关闭主库shutdown immediate
4.把datafile standbycontrolfile redologfile spfile listener.ora tnsnames.ora passwdfile拷贝至备库相应位置（如果没有相应文件夹，新建同名文件夹）
scp/u01/oradata/WILLSON/ oracle@172.25.56.150:/u01/oradata/
scp standbycontrolfile.ctl oracle@172.25.56.150:/u01/oradata/
scp listener.ora tnsnames.ora oracle@172.25.56.150:/u01/product/10.2.0/db_1/network/admin/
scp orapwWILLSON spfileWILLSON.ora oracle@172.25.56.150:/u01/product/10.2.0/db_1/dbs/
scp -r WILLSON/ oracle@172.25.56.150:/u01/admin/
5.配置pridb角色，配置归档日志地址，配置切换模式
alter system set log_archive_config='DG_CONFIG=(pridb,stydb)';
alter system set db_unique_name='pridb' scope=spfile;
shutdown immediate;
startup mount;
alter system set log_archive_dest_1='LOCATION=/u01/oradata/archivelog VALID_FOR=(ALL_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=pridb';
alter system set log_archive_dest_2='SERVICE=stydb VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLES) DB_UNIQUE_NAME=stydb';
alter system set log_archive_dest_state_1='enable';
alter system set log_archive_dest_state_2='enable';
alter system set FAL_CLIENT='pridb';
alter system set FAL_SERVER='stydb';
alter system set standby_archive_dest='/u01/oradata/archivelog';
alter system set standby_file_management='auto';
6.配置监听
[oracle@localhost admin]$ more listener.ora # listener.ora Network Configuration File: /u01/product/10.2.0/db_1/network/admin/listener.ora # Generated by Oracle configuration tools.
SID_LIST_LISTENER = (SID_LIST = (SID_DESC = (SID_NAME = PLSExtProc) (ORACLE_HOME = /u01/product/10.2.0/db_1) (PROGRAM = extproc) ) (SID_DESC = (SID_NAME = WILLSON) (ORACLE_HOME = /u01/product/10.2.0/db_1) )
)
LISTENER = (DESCRIPTION_LIST = (DESCRIPTION = (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1)) (ADDRESS = (PROTOCOL = TCP)(HOST = 172.25.56.149)(PORT = 1521)) ) )
[oracle@localhost admin]$ moretnsnames.ora # tnsnames.ora Network Configuration File: /u01/product/10.2.0/db_1/network/admin/tnsnames.ora # Generated by Oracle configuration tools.
WILLSON = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 172.25.56.149)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = WILLSON) ) )
pridb = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 172.25.56.149)(PORT = 1521)) ) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = WILLSON) ) ) stydb = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 172.25.56.150)(PORT = 1521)) ) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = WILLSON) ) )
EXTPROC_CONNECTION_DATA = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1)) ) (CONNECT_DATA = (SID = PLSExtProc) (PRESENTATION = RO) ) )
3)stydb配置
1.启动备库至mount状态（如果失败查看初始化参数文件和控制文件是否更新）
startup mount;
2.配置备库参数
alter system set log_archive_config='DG_CONFIG=(pridb,stydb)';
alter system set db_unique_name='stydb'scope=spfile;
shutdown immediate
startup mount
alter system set log_archive_dest_1='LOCATION=/u01/oradata/archivelog VALID_FOR=(ALL_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=stydb';
alter system set log_archive_dest_2='SERVICE=pridb VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLES) DB_UNIQUE_NAME=pridb';
alter system set log_archive_dest_state_1='enable';
alter system set log_archive_dest_state_2='enable';
alter system set FAL_CLIENT='stydb';
alter system set FAL_SERVER='pridb';
alter system set standby_archive_dest='/u01/oradata/archivelog';
alter system set standby_file_management='auto';
alter database force logging;
shutdown immediate
3.配置监听
[oracle@localhost admin]$ morelistener.ora # listener.ora Network Configuration File: /u01/product/10.2.0/db_1/network/admin/listener.ora # Generated by Oracle configuration tools.
SID_LIST_LISTENER = (SID_LIST = (SID_DESC = (SID_NAME = PLSExtProc) (ORACLE_HOME = /u01/product/10.2.0/db_1) (PROGRAM = extproc) ) (SID_DESC = (SID_NAME = WILLSON) (ORACLE_HOME = /u01/product/10.2.0/db_1) )
)
LISTENER = (DESCRIPTION_LIST = (DESCRIPTION = (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1)) (ADDRESS = (PROTOCOL = TCP)(HOST = 172.25.56.150)(PORT = 1521)) ) )
[oracle@localhost admin]$ more tnsnames.ora # tnsnames.ora Network Configuration File: /u01/product/10.2.0/db_1/network/admin/tnsnames.ora # Generated by Oracle configuration tools.
WILLSON = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 172.25.56.150)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = WILLSON) ) )
pridb = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 172.25.56.149)(PORT = 1521)) ) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = WILLSON) ) ) stydb = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 172.25.56.150)(PORT = 1521)) ) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = WILLSON) ) )
EXTPROC_CONNECTION_DATA = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1)) ) (CONNECT_DATA = (SID = PLSExtProc) (PRESENTATION = RO) ) )
4）测试配置
pridb：
alter database open;
select open_mode,database_role from v$database;
OPEN_MODE DATABASE_ROLE ---------- ---------------- READ WRITE PRIMARY
stydb
startup;
alter database recover managed standby database disconnect;
select open_mode,database_role from v$database;
OPEN_MODE DATABASE_ROLE ---------- ---------------- MOUNTED PHYSICAL STANDBY
同步测试：
pridb：
select sequence#,applied from v$archived_log;
stydb：
select sequence#,applied from v$archived_log;
