数据库，简而言之可视为电子化的文件柜——存储电子文件的处所，用户可以对文件中的数据进行新增、截取、更新、删除等操作。所谓“数据库”是以一定方式储存在一起、能与多个用户共享、具有尽可能小的冗余度、与应用程序彼此独立的数据集合。
在Oracle数据库中，DataGuard最主要的功能就是容灾。它可以分为物理STANDBY和逻辑STANDBY两种。物理STANDBY主要用在主库的归档日志方面；逻辑STANDBY主要应用的是主库的归档日志提取的SQL语句。本文主要论述的是DataGuard在虚拟机上的配置，包括STANDBY参数的文件的相关配置等。
1.环境准备
虚拟机版本：VMware GSX
操作系统 ：redhat linux 4
Primary主机
ip:192.168.111.131
db_name:wellcomm
db_unique_name:wellcomm
ip:192.168.111.131
db_name:wellcomm
db_unique_name:wellcommb
2.设置Primary主机为force logging模式
alter database force logging;
3.在Primary 上面创建备用日志(为切换而用)
alter database add standby logfile group 4 ('/u01/oracle/oradata/wellcomm/stdredo01.log') size 50m;
alter database add standby logfile group 5 ('/u01/oracle/oradata/wellcomm/stdredo02.log') size 50m;
alter database add standby logfile group 6 ('/u01/oracle/oradata/wellcomm/stdredo03.log') size 50m;
4.修改primary库的参数
alter system set db_unique_name='wellcomm' scope=spfile;
alter system set log_archive_config='DG_CONFIG=(wellcomm,wellcommb)';
alter system set log_archive_dest_1='LOCATION=/u01/oracle/oradata/wellcomm/arch VALID_FOR=(ALL_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=wellcomm';
alter system set log_archive_dest_2='SERVICE=wellcommb LGWR ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=wellcommb';
alter system set log_archive_dest_state_1=enable;
alter system set log_archive_dest_state_2=enable;
alter system set log_archive_max_processes=10;
5.克隆Primary数据库
shutdown immediate
startup mount
backup database;
创建standby的控制文件
alter database create standby controlfile as '/u01/oracle/controlbak.ctl';
创建standby的参数文件并按standby主机的配置修改
create pfile='/u01/oracle/initwellcommb.ora' from spfile;
6.在standby主机上恢复数据库(rman方式);
将5步的文件拷备到对应位置(ftp)
startup mount pfile='';
修改参数文件
db_name='ora10g1'
db_unique_name='ora10g3'
log_archive_config='DG_CONFIG=(wellcomm,wellcommb)'
log_archive_dest_1='LOCATION=/u01/oracle/oradata/wellcommb/arch VALID_FOR=(ALL_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=wellcommb' log_archive_dest_2='SERVICE=wellcomm LGWR ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=wellcomm'
log_archive_dest_state_1=enable
log_archive_dest_state_2=enable
remote_login_passwordfile='EXCLUSIVE'
log_archive_max_processes=10
restore database;
7.监听配置和tns服务配置
(1)primary 主机上配置
listener.ora文件内容如下：
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME = wellcomm )
(ORACLE_HOME = /u01/oracle/product/10.2.0/db_1)
(SID_NAME = wellcomm )
)
)
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.111.131)(PORT = 1521))
)
)
tnsnames.ora文件内容如下：
WELLCOMM =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = wangwang)(PORT = 1521))
(CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = wellcomm) ) ) WELLCOMMB = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.111.132)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = wellcommb)
)
)
(2)在standby主机上配置
listener.ora文件内容如下：
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME = wellcommb)
(ORACLE_HOME = /u01/oracle/product/10.2.0/db_1)
(SID_NAME = wellcommb)
)
)
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = wangkang)(PORT = 1521))
)
)
tnsnames.ora文件内容如下：
WELLCOMM =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.111.131)(PORT = 1521))
(CONNECT_DATA =
(SERVICE = DEDICATED)
(SERVICE_NAME = wellcomm)
)
)
WELLCOMMB =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.111.132)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED )
(SERVICE_NAME = wellcommb)
)
)
重启监听
lsnrctl stop
lsnrctl start
8.在standby主机上启动应用redo
alter database recover managed standby database disconnect from session;
(取消：alter database recover managed standby database cancel;)
9.确认从Primary到Standby的Redo传输及应用
(1)在Primary主机上执行日志文件切换(最好多次)
alter system switch logfile;
(2)查询Primary的归档日志
select sequence#,applied,first_time,next_time from v$archived_log order by sequence#;
(3)查询Standby的归档日志及其应用
select sequence#,applied,first_time,next_time from v$archived_log order by sequence#;
注意applied字段显示YES则表明该归档日志已被standby数据库应用了。