osqa java_ORACLE RAC TAF 配置（透明故障转移）

--ORACLE RAC TAF 配置(透明故障转移)

TAF(Transparent Application Failover)即透明应用程序故障转移技术。当初始化连接出现问题无法连接时，该功能可以保证应用程序重新连接到可用服务。在重新连接过程中，之前的活动事务将会被回滚，但在“具体条件”下TAF可以保证SELECT语句不被终止。这也是RAC亮点之一。

所谓的“具体条件”指的就是FAILOVER_MODE中METHOD选择“BASIC”、TYPE选择“SELECT”

TAF的特性：

1：TAF是ORACLE客户端提供的一项特性，使用TAF，对客户端的环境有一定的要求，比如JAVA的JDBC驱动、Oracle客户端的版本等(8i开始支持TAF)；

2：大致上TAF可以分为2种，连接时的TAF和会话建立后TAF；

3：TAF本身与是否RAC环境无关，但一般都用在RAC环境，最小程度的减少最应用的影响，单实例环境下也可以使用TAF，这样使用PL/SQL developer连接数据库，即使数据库实例重启，也不需要重新连接；

4：RAC环境下，还可以把TAF配置在服务器端；

5：配置listener.ora文件的GLOBAL_DBNAME参数后将会禁用TAF

查看当前service

col name format a24

col failover_method format a11 heading 'METHOD'

col failover_type format a10 heading 'TYPE'

col failover_retries format 9999999 heading 'RETRIES'

col goal format a10

col clb_goal format a8

col AQ_HA_NOTIFICATIONS format a5 heading 'AQNOT'

selectname,failover_method,failover_type,failover_retries,goal,clb_goal,aq_ha_notificationsfromdba_services;

1. 客户端TAF配置

vi tnsnames.ora

NODE =

(DESCRIPTION =

(ADDRESS_LIST =

(ADDRESS = (PROTOCOL = TCP)(HOST = rac-scan.yang.com)(PORT = 1521))

)

(CONNECT_DATA =

(SERVICE_NAME = rac.yang.com)

(FAILOVER_MODE =

(TYPE = SELECT)

(METHOD = BASIC)

(RETRIES = 180)

(DELAY = 5))

)

)

SELECTMACHINE,FAILOVER_TYPE,FAILOVER_METHOD,FAILED_OVERFROMV$SESSIONWHERESID=141;

MACHINE TYPE METHOD FAI

-------------------- ---------- ----------- ---

tay SELECTBASICNO

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