9. Oracle DataGuard的介绍

一. Oracle DataGuard简介

　　Oracle DataGuard；简称DG。是由一个Primary Database（主库）和一个或者多个Standby Database（备库）组成。对Oracle来说；本身不能提高性能。通过数据冗余来保护数据。由Primary Database对外提供服务；用户操作在Primary Database上操作；其操作的数据库Redo Log或者Archive log通过网络传输到Standby Database。Standby Database在重做这些日志。从而实现Primary Database和Standby Database数据同步。

架构图如下：

Oracle DataGuard中的Standby库有两种：物理Standby和逻辑Standby。

• 逻辑Standby接收后将其转换成SQL语句，在Standby数据库上执行SQL语句实现同步，这种方式叫SQL Apply。
• 物理Standby接收完Primary数据库生成的REDO数据后，以介质恢复的方式实现同步，这种方式也叫Redo Apply。

二. Oracle DataGuard搭建

　　安装规划：

IP	ROLE
192.168.1.235	Primary
192.168.1.221	Standby

2.1. 主库设置归档模式

alter database archivelog;

2.2. 主库设置Force Logging模式

alter database force logging;

2.3. 备库创建相应的dump文件夹

# 在主库查询对应的dump目录
select name, value
  from v$parameter
 where name in ('audit_file_dest',
                'background_dump_dest',
                'control_files',
                'core_dump_dest',
                'user_dump_dest',
                'db_recovery_file_dest'
                               )
 ORDER BY name ASC;
# 备库用oracle用户执行创建目录
mkdir -p $value

2.4. 配置Standby Redologs

　　对于模式中最大保护和最高可用性；采用是 LGWR 模式传送 Redo 日志；需要为 Standby库配置 Standby Redologs。Standby Redologs 和 ONline Redologs 文件大小是相同的。比 ONline Redologs 个数要 +1 。

# 查看redologs日志信息
SQL> select group#,type,member from v$logfile;

GROUP# TYPE   MEMBER
------ ---------- --------------------------------------------------
     1 ONLINE   /u01/app/oradata/ora235/redo01.log
     2 ONLINE   /u01/app/oradata/ora235/redo02.log
     3 ONLINE   /u01/app/oradata/ora235/redo03.log

SQL> select group#,bytes from v$log;

GROUP#     BYTES
------ ----------
     1  52428800
     2  52428800
     3  52428800
# 添加Standby Redologs；添加如下：
ALTER DATABASE ADD STANDBY LOGFILE GROUP 4('/u01/app/oradata/ora235/stdred001.log') SIZE 50 M;
ALTER DATABASE ADD STANDBY LOGFILE GROUP 5('/u01/app/oradata/ora235/stdred002.log') SIZE 50 M;
ALTER DATABASE ADD STANDBY LOGFILE GROUP 6('/u01/app/oradata/ora235/stdred003.log') SIZE 50 M;
ALTER DATABASE ADD STANDBY LOGFILE GROUP 7('/u01/app/oradata/ora235/stdred004.log') SIZE 50 M;

2.5. 创建实例密钥文件

• 主库生成密钥文件

orapwd FILE=/u01/app/oracle/dbs/orapwora235 password=li0924 entries=5;

• 将密钥文件传输到备库

scp /u01/app/oracle/dbs/orapwora235 oracle@192.168.1.221:/u01/app/oracle/dbs

2.6. 创建参数文件

　　本文采用 Primary 库和 Standby 库采用相同路径；所以仅设置必要的参数。

• 主库通过spfile生成pfile文件

create pfile from spfile;

• 添加Primary端的pfile内容如下

*.DB_UNIQUE_NAME=db_primary
*.LOG_ARCHIVE_CONFIG='DG_CONFIG=(db_primary,db_standby)'
*.LOG_ARCHIVE_DEST_2='SERVICE=tns_standby LGWR ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=db_standby'
*.LOG_ARCHIVE_DEST_STATE_2=DEFER
*.LOG_FILE_NAME_CONVERT ='/u01/app/oradata/ora235/','/u01/app/oradata/ora235/'
*.FAL_SERVER=tns_standby
*.FAL_CLIENT=tns_primary
*.STANDBY_FILE_MANAGEMENT=AUTO

• Primary重新启动

primary>create spfile from pfile;

File created.

primary>startup
ORACLE instance started.

Total System Global Area  780824576 bytes
Fixed Size      2257312 bytes
Variable Size    511708768 bytes
Database Buffers   264241152 bytes
Redo Buffers      2617344 bytes
Database mounted.
Database opened.

• 复制参数文件到Standby库

scp /u01/app/oracle/dbs/initora235.ora oracle@192.168.1.221:/u01/app/oracle/dbs

• 添加Standby端的pfile内容如下

*.DB_UNIQUE_NAME=db_standby
*.LOG_ARCHIVE_CONFIG='DG_CONFIG=(db_primary,db_standby)'
*.LOG_ARCHIVE_DEST_2='SERVICE=tns_primary LGWR ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=db_primary'
*.LOG_FILE_NAME_CONVERT ='/u01/app/oradata/ora235/','/u01/app/oradata/ora235/'
*.LOG_ARCHIVE_DEST_STATE_2=ENABLE
*.FAL_SERVER=tns_primary
*.FAL_CLIENT=tns_standby
*.STANDBY_FILE_MANAGEMENT=AUTO

• 将Standby端启动到nomount状态

[oracle@oracle221 ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Thu Aug 9 22:56:49 2018

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup nomount;
ORACLE instance started.

Total System Global Area  780824576 bytes
Fixed Size      2257312 bytes
Variable Size    511708768 bytes
Database Buffers   264241152 bytes
Redo Buffers      2617344 bytes

2.7 配置主备库的监听文件和网络文件

• 设置Primary库和Standby库的service_name

SQL> show parameter service_name;

NAME         TYPE  VALUE
------------------------------------ ----------- ---------------
service_names        string  lottu
SQL> alter system set service_names='db_primary' scope=both;

System altered.

SQL> show parameter service_name;

NAME         TYPE  VALUE
------------------------------------ ----------- ----------------
service_names        string  db_primary

• 备库的service_name设置为db_standby；需要到参数文件修改。

*.service_names='db_standby'

• Primary库配置listener.ora

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
       (ADDRESS_LIST =(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.235)(PORT = 1521)(IP = FIRST)))
       (ADDRESS_LIST =
         (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
       )
     )
  )

SID_LIST_LISTENER =
  (SID_LIST =
   (SID_DESC =
     (SID_NAME = ora235)
     (GLOBAL_DBNAME = db_primary)
     (ORACLE_HOME =/u01/app/oracle)
   )
  )

• Standby库配置listener.ora

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
       (ADDRESS_LIST =(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.221)(PORT = 1521)(IP = FIRST)))
       (ADDRESS_LIST =
         (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
       )
     )
  )

SID_LIST_LISTENER =
  (SID_LIST =
   (SID_DESC =
     (SID_NAME = ora235)
     (GLOBAL_DBNAME = db_standby)
     (ORACLE_HOME =/u01/app/oracle)
   )
  )

• Primary库和Standby库设置tnsname.ora

tns_primary=
  (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.235)(PORT = 1521))
      (CONNECT_DATA =
  (SERVICE_NAME = db_primary)
      )
     (HS = OK)
  )

tns_standby=
  (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.221)(PORT = 1521))
    (CONNECT_DATA =
    (SERVICE_NAME = db_standby)
    )
 (HS = OK)
  ) 

　　重启监听lsnrctl restart

2.8. 克隆Standby库

在Primary库执行

[oracle@oracle235 admin]$ rman target sys/li0924@tns_primary auxiliary sys/li0924@tns_standby

Recovery Manager: Release 11.2.0.4.0 - Production on Thu Aug 9 23:56:46 2018

Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.

connected to target database: ORA235 (DBID=2047494122)
connected to auxiliary database: ORA235 (not mounted)

RMAN> DUPLICATE TARGET DATABASE FOR STANDBY FROM ACTIVE DATABASE DORECOVER NOFILENAMECHECK;

Starting Duplicate Db at 09-AUG-18
using target database control file instead of recovery catalog
allocated channel: ORA_AUX_DISK_1
channel ORA_AUX_DISK_1: SID=20 device type=DISK

contents of Memory Script:
{
   backup as copy reuse
   targetfile  '/u01/app/oracle/dbs/orapwora235' auxiliary format
 '/u01/app/oracle/dbs/orapwora235'   ;
}
executing Memory Script

Starting backup at 09-AUG-18
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=26 device type=DISK
Finished backup at 09-AUG-18

contents of Memory Script:
{
   backup as copy current controlfile for standby auxiliary format  '/u01/app/oradata/ora235/control01.ctl';
   restore clone controlfile to  '/u01/app/oradata/ora235/control02.ctl' from
 '/u01/app/oradata/ora235/control01.ctl';
}
executing Memory Script

Starting backup at 09-AUG-18
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
copying standby control file
output file name=/u01/app/oracle/dbs/snapcf_ora235.f tag=TAG20180809T235658 RECID=4 STAMP=983750219
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:01
Finished backup at 09-AUG-18

Starting restore at 09-AUG-18
using channel ORA_AUX_DISK_1

channel ORA_AUX_DISK_1: copied control file copy
Finished restore at 09-AUG-18

contents of Memory Script:
{
   sql clone 'alter database mount standby database';
}
executing Memory Script

sql statement: alter database mount standby database

contents of Memory Script:
{
   set newname for tempfile  1 to
 "/u01/app/oradata/ora235/temp01.dbf";
   switch clone tempfile all;
   set newname for datafile  1 to
 "/u01/app/oradata/ora235/system01.dbf";
   set newname for datafile  2 to
 "/u01/app/oradata/ora235/sysaux01.dbf";
   set newname for datafile  3 to
 "/u01/app/oradata/ora235/undotbs01.dbf";
   set newname for datafile  4 to
 "/u01/app/oradata/ora235/users01.dbf";
   set newname for datafile  5 to
 "/data/oracle/data/lottu01.dbf";
   backup as copy reuse
   datafile  1 auxiliary format
 "/u01/app/oradata/ora235/system01.dbf"   datafile
 2 auxiliary format
 "/u01/app/oradata/ora235/sysaux01.dbf"   datafile
 3 auxiliary format
 "/u01/app/oradata/ora235/undotbs01.dbf"   datafile
 4 auxiliary format
 "/u01/app/oradata/ora235/users01.dbf"   datafile
 5 auxiliary format
 "/data/oracle/data/lottu01.dbf"   ;
   sql 'alter system archive log current';
}
executing Memory Script

executing command: SET NEWNAME

renamed tempfile 1 to /u01/app/oradata/ora235/temp01.dbf in control file

executing command: SET NEWNAME

executing command: SET NEWNAME

executing command: SET NEWNAME

executing command: SET NEWNAME

executing command: SET NEWNAME

Starting backup at 09-AUG-18
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
input datafile file number=00005 name=/data/oracle/data/lottu01.dbf
output file name=/data/oracle/data/lottu01.dbf tag=TAG20180809T235706
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:01:45
channel ORA_DISK_1: starting datafile copy
input datafile file number=00001 name=/u01/app/oradata/ora235/system01.dbf
output file name=/u01/app/oradata/ora235/system01.dbf tag=TAG20180809T235706
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:35
channel ORA_DISK_1: starting datafile copy
input datafile file number=00002 name=/u01/app/oradata/ora235/sysaux01.dbf
output file name=/u01/app/oradata/ora235/sysaux01.dbf tag=TAG20180809T235706
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:35
channel ORA_DISK_1: starting datafile copy
input datafile file number=00003 name=/u01/app/oradata/ora235/undotbs01.dbf
output file name=/u01/app/oradata/ora235/undotbs01.dbf tag=TAG20180809T235706
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:25
channel ORA_DISK_1: starting datafile copy
input datafile file number=00004 name=/u01/app/oradata/ora235/users01.dbf
output file name=/u01/app/oradata/ora235/users01.dbf tag=TAG20180809T235706
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:01
Finished backup at 10-AUG-18

sql statement: alter system archive log current

contents of Memory Script:
{
   backup as copy reuse
   archivelog like  "/data/arch/1_3_983660602.dbf" auxiliary format
 "/data/arch/1_3_983660602.dbf"   ;
   catalog clone archivelog  "/data/arch/1_3_983660602.dbf";
   switch clone datafile all;
}
executing Memory Script

Starting backup at 10-AUG-18
using channel ORA_DISK_1
channel ORA_DISK_1: starting archived log copy
input archived log thread=1 sequence=3 RECID=19 STAMP=983750428
output file name=/data/arch/1_3_983660602.dbf RECID=0 STAMP=0
channel ORA_DISK_1: archived log copy complete, elapsed time: 00:00:01
Finished backup at 10-AUG-18

cataloged archived log
archived log file name=/data/arch/1_3_983660602.dbf RECID=1 STAMP=983750429

datafile 1 switched to datafile copy
input datafile copy RECID=4 STAMP=983750429 file name=/u01/app/oradata/ora235/system01.dbf
datafile 2 switched to datafile copy
input datafile copy RECID=5 STAMP=983750429 file name=/u01/app/oradata/ora235/sysaux01.dbf
datafile 3 switched to datafile copy
input datafile copy RECID=6 STAMP=983750429 file name=/u01/app/oradata/ora235/undotbs01.dbf
datafile 4 switched to datafile copy
input datafile copy RECID=7 STAMP=983750429 file name=/u01/app/oradata/ora235/users01.dbf
datafile 5 switched to datafile copy
input datafile copy RECID=8 STAMP=983750429 file name=/data/oracle/data/lottu01.dbf

contents of Memory Script:
{
   set until scn  955597;
   recover
   standby
   clone database
    delete archivelog
   ;
}
executing Memory Script

executing command: SET until clause

Starting recover at 10-AUG-18
using channel ORA_AUX_DISK_1

starting media recovery

archived log for thread 1 with sequence 3 is already on disk as file /data/arch/1_3_983660602.dbf
archived log file name=/data/arch/1_3_983660602.dbf thread=1 sequence=3
media recovery complete, elapsed time: 00:00:00
Finished recover at 10-AUG-18
Finished Duplicate Db at 10-AUG-18

2.9. 启用日志传送

在 Primary 端启动日志传送

alter system set LOG_ARCHIVE_DEST_STATE_2=ENABLE;

2.10. 启用实时应用redo

　　在 Primary Database 产生的 Redo 日志；传送到 Standby Database；是通过 LGWR 或者 ARCH 进程完成。这个很好理解。默认情况下是由 ARCH 进程。有参数 *.LOG_ARCHIVE_DEST_2 控制的。使用 ARCH 进程； Primary Database 和 Standby Database 存在数据延迟。若 Primary Database 出现异常；容易造成部分数据丢失。为了避免数据丢失，必须要使用 LGWR 进程，需要用到 Standby Redolog。而LGWR 又分SYNC（同步）和ASYNC（异步）两种方式。

• SYNC方式：对网络要求比较高；必须等待写入本地日志文件操作和通过LNSn进程的网络传送都成功，Primary Database 上的事务才能提交成功。使用LGWR SYNC方式时，可以同时使用NET_TIMEOUT参数，这个参数单位是秒，代表如果多长时间内网络发送没有响应，LGWR 进程会抛出错误。因此对 Primary Database 性能有影响。

*.LOG_ARCHIVE_DEST_2='SERVICE=tns_standby LGWR SYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=db_standby NET_TIMEOUT = 30'

• ASYNC方式：采用异步方式；Primary Database 上的事务提交跟日志是否已经传送没有影响。

*.LOG_ARCHIVE_DEST_2='SERVICE=tns_standby LGWR ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=db_standby'

1. 在 Primary Database上执行；

alter system set log_archive_dest_2='SERVICE=tns_standby LGWR ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=db_standby' scope=both;

2. 在Standby Database上执行；

alter system set log_archive_dest_2='SERVICE=tns_primary LGWR ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=db_primary' scope=both;

3. Standby Database启动实时应用redo

alter database recover managed standby database using current logfile ;

4. 验证结果

# 在Primary Database 上创建表t_lottu02
SQL> set SQLPROMPT Primary>
Primary>conn lottu/li0924
Connected.
Primary>create table t_lottu02 as select level id,'lottu' name from dual connect by level <= 3;

Table created.

# 在Standby Database上查看
SQL> set SQLPROMPT StandBy>
StandBy>conn lottu/li0924
Connected.
StandBy>select * from t_lottu02;

 ID NAME
---------- -----
  1 lottu
  2 lottu
  3 lottu