我们的文章会在微信公众号IT民工的龙马人生和博客网站( www.htz.pw )同步更新 ，欢迎关注收藏，也欢迎大家转载，但是请在文章开始地方标注文章出处，谢谢！
由于博客中有大量代码，通过页面浏览效果更佳。

故障分析：11GR DATAGRUAD环境BROKER配置Fast-Start Failover

FAST-START failover 就是在当主数据库出现故障时，能快速与可靠的把standby切换成主数据库，在整个过程中不需要人来干预。fast-start failover只能通过dgmgrl与Enterprise Managerg来配置。

只有maximum availability mode or maximum performance mode才能启用fast-start failover模式。在maximum availability模式下面，在切换时可以保证无数据丢失，在maximum performance mode下面，会有数据丢失，丢失多少数据由 FastStartFailoverLagLimit这个参数来配置。

只要observer进程启动过，我们就不需要人为的干预。当observer与指定的备数据库与主数据库失去连接的时间超过FastStartFailoverThreshold后，observer就会启动fast-start failover 到备数据库。如果配置了FastStartFailoverPmyShutdown为true，此时原来的主数据库将会自动的shutdown。如果配置FastStartFailoverAutoReinstate为true，当failover完成后，启动数据库时，会自动的执行Reinstate database，把原来的主数据库变成备库，并与新主库进行同步。

fast-start failover包含3个过程，如下图：

测试开始：

环境：OS REDHAT 5.6 X86_64 ,DB 11.2.0.2

1,DG环境的搭建。

见11GR2 搭建活动的物理DG/DATAGRUAD (READ ONLY模式)

2,broker的配置

3，配置保护模式与日志传递方式

之前已经说了FAST-START FAILOVER只 maximum availability mode与maximum performance mode

下面我们看一下每一种保护模式对应的日志传递方式。

3.1修改保护模式：

[oracle@test admin]$ dgmgrl 
DGMGRL for Linux: Version 11.2.0.2.0 - 64bit Production 
 
Copyright (c) 2000, 2009, Oracle. All rights reserved. 
 
Welcome to DGMGRL, type "help" for information. 
DGMGRL> connect sys/oracle@htz  
Connected. 
#通过help查看命令的帮忙。 
DGMGRL> help edit 
Edits a configuration, database, or instance 
Syntax: 
 
  EDIT CONFIGURATION SET PROTECTION MODE AS  
    {MaxProtection|MaxAvailability|MaxPerformance}; 
 
  EDIT CONFIGURATION SET PROPERTY <property name> = <value>; 
 
  EDIT DATABASE <database name> SET PROPERTY <property name> = <value>; 
 
  EDIT DATABASE <database name> RENAME TO <new database name>; 
 
  EDIT DATABASE <database name> SET STATE = <state> 
    [WITH APPLY INSTANCE = <instance name>]; 
 
  EDIT INSTANCE <instance name> [ON DATABASE <database name>] 
    SET AUTO PFILE [ = {<initialization file path>|OFF} ]; 
 
  EDIT INSTANCE <instance name> [ON DATABASE <database name>] 
    SET PROPERTY <property name> = <value>; 
 
  EDIT INSTANCE * ON DATABASE <database name> 
    SET PROPERTY <property name> = <value>; 
 
DGMGRL> edit configuration set protection mode as maxavilability; 
Syntax error before or at "maxavilability" 
DGMGRL> show configuration; 
 
Configuration - htz 

最大可用的保护模式

  Protection Mode: MaxAvailability 
  Databases: 
    htzb - Primary database 
    htz  - Physical standby database 
Fast-Start Failover: DISABLED 
Configuration Status: 
SUCCESS 

3.2 修改日志传递方式

DGMGRL> edit database htz set property logxptmode=sync; 
Property "logxptmode" updated 
DGMGRL> edit database htzb set property logxptmode=sync; 
Property "logxptmode" updated 
DGMGRL> show database htz logxptmode 
  LogXptMode = 'sync' 
DGMGRL> show database htzb logxptmode 
  LogXptMode = 'sync 

4 配置数据库的flashback

4.1 主库上面

SQL> select open_mode,database_role,log_mode,flashback_on from v$database; 
 
OPEN_MODE            DATABASE_ROLE    LOG_MODE     FLASHBACK_ON 
-------------------- ---------------- ------------ ------------------ 
READ WRITE           PRIMARY          ARCHIVELOG   NO 

配置flashback

SQL> alter database flashback on; 
 
Database altered. 
 
SQL> select open_mode,database_role,log_mode,flashback_on from v$database; 
 
OPEN_MODE            DATABASE_ROLE    LOG_MODE     FLASHBACK_ON 
-------------------- ---------------- ------------ ------------------ 
READ WRITE           PRIMARY          ARCHIVELOG   YES 

flashback的配置目录与大小

SQL> show parameter recovery 
 
NAME                                 TYPE        VALUE 
------------------------------------ ----------- ------------------------------ 
db_recovery_file_dest                string      /u01/app/oracle/fast_recovery_ 
                                                 area 
db_recovery_file_dest_size           big integer 4032M 

4.2 备库上面

SQL> select open_mode,database_role,log_mode,flashback_on from v$database; 
 
OPEN_MODE            DATABASE_ROLE    LOG_MODE     FLASHBACK_ON 
-------------------- ---------------- ------------ ------------------ 
READ ONLY WITH APPLY PHYSICAL STANDBY ARCHIVELOG   NO 
 
SQL> recover managed standby database cancel; 
Media recovery complete. 
SQL> alter database flashback on; 
 
Database altered. 
 
SQL> recover managed standby database using current logfile disconnect; 
Media recovery complete. 
SQL> select open_mode,database_role,log_mode,flashback_on from v$database; 
 
OPEN_MODE            DATABASE_ROLE    LOG_MODE     FLASHBACK_ON 
-------------------- ---------------- ------------ ------------------ 
READ ONLY WITH APPLY PHYSICAL STANDBY ARCHIVELOG   YES 

5 配置observer服务器

5.1 配置tnsnames.ora文件。

[oracle@test admin]$ cat tnsnames.ora 
HTZB = 
  (DESCRIPTION = 
    (ADDRESS_LIST = 
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.100.31)(PORT = 1521)) 
    ) 
    (CONNECT_DATA = 
      (SERVER = dedicate) 
      (SERVICE_NAME = htzb) 
    ) 
  ) 
 
HTZ = 
  (DESCRIPTION = 
    (ADDRESS_LIST = 
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.100.30)(PORT = 1521)) 
    ) 
    (CONNECT_DATA = 
      (SERVER = dedicate) 
      (SERVICE_NAME = htz) 
    ) 
  ) 

5.2 启动observer进程

[oracle@test admin]$ dgmgrl sys/oracle@htz "start observer" 
DGMGRL for Linux: Version 11.2.0.2.0 - 64bit Production 
 
Copyright (c) 2000, 2009, Oracle. All rights reserved. 
 
Welcome to DGMGRL, type "help" for information. 
Connected. 
Observer started 

6 配置fast-start failover

DGMGRL> edit database htz set property FastStartFailoverTarget=htzb; 
Property "faststartfailovertarget" updated 
DGMGRL> edit database htzb set property  FastStartFailoverTarget=htz; 
Property "faststartfailovertarget" updated 
于fst-start failove相关的其它几个参数:

FastStartFailoverPmyShutdown

FastStartFailoverLagLimit

FastStartFailoverAutoReinstate

ObserverConnectIdentifier

这里我们都使用默认值;我们来看一下这些值的默认值；

DGMGRL> show configuration verbose; 
 
Configuration - htz 
 
  Protection Mode: MaxAvailability 
  Databases: 
    htzb - Primary database 
    htz  - (*) Physical standby database 
 
  (*) Fast-Start Failover target 
 
  Properties: 
    FastStartFailoverThreshold      = '30' 
    OperationTimeout                = '30' 
    FastStartFailoverLagLimit       = '30' 
    CommunicationTimeout            = '180' 
    FastStartFailoverAutoReinstate  = 'TRUE' 
    FastStartFailoverPmyShutdown    = 'TRUE' 
    BystandersFollowRoleChange      = 'ALL' 
 
Fast-Start Failover: DISABLE
 
  Threshold:        30 seconds 
  Target:           htz 
  Observer:         test 
  Lag Limit:        30 seconds (not in use) 
  Shutdown Primary: TRUE 
  Auto-reinstate:   TRUE 
 
Configuration Status: 
SUCCESS 

7 启用fast-start failover

DGMGRL> show configuration 
 
Configuration - htz 
 
  Protection Mode: MaxAvailability 
  Databases: 
    htzb - Primary database 
    htz  - Physical standby database 
 
Fast-Start Failover: DISABLED 
 
Configuration Status: 
SUCCESS 
DGMGRL> enable fast_start failover 
Enabled. 
DGMGRL>  

8.测试FAST-START FAILOVER是否生效

DGMGRL> show configuration 
 
Configuration - htz 
 
  Protection Mode: MaxAvailability 
  Databases: 
    htzb - Primary database 
    htz  - (*) Physical standby database 
Fast-Start Failover: ENABLED 
Configuration Status: 
SUCCESS 

原主库直接shutdown abort;

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

observer进程的日志

19:03:03.93  Friday, September 07, 2012
Initiating Fast-Start Failover to database "htz"...
Performing failover NOW, please wait...
Failover succeeded, new primary is "htz"
19:03:13.24  Friday, September 07, 2012

提示已经把主切换到htz

在htz上面查看一下

SQL> select open_mode ,database_role from v$database; 
 
OPEN_MODE            DATABASE_ROLE 
-------------------- ---------------- 
READ WRITE           PRIMARY 

已经成功
手动启动原主库

DGMGRL> show configuration;

Configuration - htz

  Protection Mode: MaxAvailability
  Databases:
    htz  - Primary database
      Warning: ORA-16817: unsynchronized fast-start failover configuration

    htzb - (*) Physical standby database (disabled)
      ORA-16661: the standby database needs to be reinstated

Fast-Start Failover: ENABLED

Configuration Status:
WARNING

DGMGRL> connect sys/oracle@htzb
Connected.
DGMGRL> startup
ORACLE instance started.
Database mounted.
ORA-16649: possible failover to another database prevents this database from being opened

过一分会后我们再查看一下状态

DGMGRL> connect sys/oracle@htz
Connected.
DGMGRL> show configuration

Configuration - htz

  Protection Mode: MaxAvailability
  Databases:
    htz  - Primary database
    htzb - (*) Physical standby database

Fast-Start Failover: ENABLED

Configuration Status:
SUCCESS

查看状态，一切正常。

------------------作者介绍-----------------------
姓名：黄廷忠
现就职：Oracle中国高级服务团队
曾就职：OceanBase、云和恩墨、东方龙马等
电话、微信、QQ：18081072613
个人博客: (http://www.htz.pw)
CSDN地址: (https://blog.csdn.net/wwwhtzpw)
博客园地址: (https://www.cnblogs.com/www-htz-pw)