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[size=130%]Understanding Transparent Application Failover (TAF) and Fast Connection Failover (FCF) (Doc ID 334471.1)


在10g版本中借助于vip的配置达到load balance+failover的配置如下：
racdb =   

(DESCRIPTION =

  

   (ADDRESS= (PROTOCOL= TCP)(HOST=192.168.3.101)(PORT= 1521))

  

   (ADDRESS= (PROTOCOL= TCP)(HOST=192.168.3.201)(PORT= 1521))

  

   (LOAD_BALANCE = yes)

  

   (FAILOVER = ON)

  

    (CONNECT_DATA =

  

     (SERVER= DEDICATED)

  

      (SERVICE_NAME = racdb)

  

      (FAILOVER_MODE =

  

        (TYPE= SELECT)

  

        (METHOD= BASIC)

  

        (RETRIES = 30)

  

        (DELAY = 5))))

11g的scan-ip如果也想进一步扩展failover,也需要设置failover_mode和对应的type.  
  
当然有一个不同之处是在10g中我们可以直接通过dbca来完成配置，就是简单清晰。  
在11g中，只能借助于命令或者EM来实现了。不知道为什么把这块功能的图形界面部分给去掉了。  
通过命令其实也不算麻烦，我们可以使用下面的方式做一个简单的配置。  
比如我们选择failover_mode为basic创建的taf为racdb_taf  
  

srvctl add service -d RACDB -s racdb_taf -r "RACDB1,RACDB2" -P BASIC
bash-4.1$ crs_stat -t|grep taf
Name           Type           Target    State     Host        
------------------------------------------------------------   
ora....taf.svc ora....ce.type OFFLINE   OFFLINE     
我们手工开启         
srvctl start service -d RACDB -s racdb_taf
      
    然后通过dbms_service来配置更多的属性。
execute dbms_service.modify_service (service_name => 'racdb_taf', aq_ha_notifications => true, failover_method => dbms_service.failover_method_basic, failover_type => dbms_service.failover_type_select, failover_retries => 181,failover_delay => 5,clb_goal => dbms_service.clb_goal_long);
    在数据库中可以简单查看相关的service情况。
SQL> select service_id ,name from dba_services ;

------
2. 服务器端TAF配置
       
2.1添加taf服务
srvctl add service -d cnposqa -s cnposqa_taf -r "cnposqa1,cnposqa2" -P BASIC
            -e        Failover type (NONE, SESSION, or SELECT)
    -m      Failover method (NONE or BASIC)
    srvctl add service -d cnposqa -s cnposqa_taftt -r "cnposqa1,cnposqa2" -e select -m basic -P BASIC

       
2.2启动服务
srvctl start service -d cnposqa -s cnposqa_taf


        2.3检查服务情况
> srvctl config service -d cnposqa -s cnposqa_taf
Service name: cnposqa_taf
Service is enabled
Server pool: cnposqa_cnposqa_taf
Cardinality: 2
Disconnect: false
Service role: PRIMARY
Management policy: AUTOMATIC
DTP transaction: false
AQ HA notifications: false
Failover type: NONE
Failover method: NONE
TAF failover retries: 0
TAF failover delay: 0
Connection Load Balancing Goal: LONG
Runtime Load Balancing Goal: NONE
TAF policy specification: BASIC
Edition:
Preferred instances: cnposqa1,cnposqa2
Available instances:

        2.3 给service添加参数(basic,select)：
        execute dbms_service.modify_service (service_name => 'cnposqa_taf' -
, aq_ha_notifications => true -
, failover_method => dbms_service.failover_method_basic -
, failover_type => dbms_service.failover_type_select -
, failover_retries => 180 -
, failover_delay => 5 -
, clb_goal => dbms_service.clb_goal_long);
       
        ++单边服务添加
        --cnposqa_taf2单边服务，主节点cnposqa2, 副节点cnposqa1   (-r Preferred  , -a Available )
srvctl add service -d cnposqa -s cnposqa_taf2 -r "cnposqa2" -a "cnposqa1" -P BASIC
        config service -d cnposqa -s cnposqa_taf2
Service name: cnposqa_taf2
Service is enabled
Server pool: cnposqa_cnposqa_taf2
Cardinality: 1
Disconnect: false
Service role: PRIMARY
Management policy: AUTOMATIC
DTP transaction: false
AQ HA notifications: false
Failover type: NONE
Failover method: NONE
TAF failover retries: 0
TAF failover delay: 0
Connection Load Balancing Goal: LONG
Runtime Load Balancing Goal: NONE
TAF policy specification: BASIC
Edition:
Preferred instances: cnposqa2
Available instances: cnposqa1


        切换测试
        --停服务
stop service -d cnposqa -s cnposqa_taf2  
--服务启动到instance 1
start service -d cnposqa -s cnposqa_taf2 -i cnposqa1