ORACLE RAC 负载均衡与local_listener、remote_listener两个参数的配置关系

ORACLE RAC 负载均衡与local_listener、remote_listener两个参数的配置关系
RAC的负载均衡主要由客户端和服务器端两种实现方式。

1，客户端的实现，直接在tnsnames.ora中配置LOAD_BALANCE参数来实现。默认值是NO
clinet_LB =
(DESCRIPTION =
(LOAD_BALANCE = YES)
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.4.124.243)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.4.124.244)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.4.124.245)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.4.124.246)(PORT = 1521))
(CONNECT_DATA =
(SERVICE_NAME = srv_epm1)
)
)
2，服务器端的负载均衡LB设置。主要是通过两个初始化参数local_listener、remote_listener来实现的。通过这两个参数，oracle分别向这两个参数指向的listener进行注册，这样，listener就能知道各个服务的状态，进而进行连接分发。
11gr2版本，这两个参数默认设置为如下

SQL> show parameter listener

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
listener_networks string
local_listener string (DESCRIPTION=(ADDRESS_LIST=(AD
DRESS=(PROTOCOL=TCP)(HOST=10.4
.124.244)(PORT=1521))))
remote_listener string dtydb-scan2:1521

由于以上设置，数据库实例分别向local_listener和remote_listener进行注册。

本地listener只注册了+ASM2和epmdb2两个实例

LSNRCTL> set current_listener LISTENER
Current Listener is LISTENER
LSNRCTL> service
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER)))
Services Summary...
Service "+ASM" has 1 instance(s).
Instance "+ASM2", status READY, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:10765 refused:0 state:ready
LOCAL SERVER
Service "epmdb" has 1 instance(s).
Instance "epmdb2", status READY, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:10 refused:0 state:ready
LOCAL SERVER
The command completed successfully

SCAN listener注册了所有数据库实例默认service和运行在epmdb1实例上的服务srv_epm1
查看服务注册情况，SCAN

LSNRCTL> set current_listener LISTENER_SCAN1
Current Listener is LISTENER_SCAN1
LSNRCTL> service
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER_SCAN1)))
Services Summary...
Service "epmdb" has 3 instance(s).
Instance "epmdb1", status READY, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:0 refused:0 state:ready
REMOTE SERVER
(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.4.124.243)(PORT=1521)))
Instance "epmdb2", status READY, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:0 refused:0 state:ready
REMOTE SERVER
(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.4.124.244)(PORT=1521)))
Instance "epmdb3", status READY, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:4 refused:0 state:ready
REMOTE SERVER
(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.4.124.245)(PORT=1521)))
Service "srv_epm1" has 1 instance(s).
Instance "epmdb1", status READY, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:0 refused:0 state:ready
REMOTE SERVER
(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.4.124.243)(PORT=1521)))
The command completed successfully

tnsnames.ora的配置如下
tydb_srv_epm1 =
(DESCRIPTION =
(LOAD_BALANCE = NO)
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.4.124.243)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.4.124.244)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.4.124.245)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.4.124.246)(PORT = 1521))
(CONNECT_DATA =
(SERVICE_NAME = epmdb)
)
)
epmdb_scan =
(DESCRIPTION =
(LOAD_BALANCE = NO)
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.4.124.230)(PORT = 1521))
(CONNECT_DATA =
(SERVICE_NAME = epmdb)
)
)


当我们连接时tydb_srv_epm1，由于顺序关系，会连接到epmdb1实例

sqlplus system/oracle@tydb_srv_epm1

SQL*Plus: Release 10.2.0.1.0 - Production on 星期四 6月 14 16:10:21 2012

Copyright (c) 1982, 2005, Oracle. All rights reserved.


连接到:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management,
OLAP,
Data Mining and Real Application Testing options

SQL> select instance_name from v$instance;

INSTANCE_NAME
----------------
epmdb1

SQL> exit

连接scan IP时，由于scan listener了注册了各个数据库实例，负载均衡的效果就产生了

>sqlplus system/oracle@epmdb_scan

SQL*Plus: Release 10.2.0.1.0 - Production on 星期四 6月 14 16:11:26 2012

Copyright (c) 1982, 2005, Oracle. All rights reserved.


连接到:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management,
OLAP,
Data Mining and Real Application Testing options

SQL> select instance_name from v$instance;

INSTANCE_NAME
----------------
epmdb1

SQL> exit
从 Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management,
OLAP,
Data Mining and Real Application Testing options 断开

sqlplus system/oracle@epmdb_scan

SQL*Plus: Release 10.2.0.1.0 - Production on 星期四 6月 14 16:12:57 2012

Copyright (c) 1982, 2005, Oracle. All rights reserved.


连接到:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management,
OLAP,
Data Mining and Real Application Testing options

SQL> select instance_name from v$instance;

INSTANCE_NAME
----------------
epmdb3

SQL>


3，10gr2版本以上，TAF主要是通过service的配置来实现。已如下已配置的service srv_epm1为例

[grid@dtydb3 ~]$ srvctl config service -d epmdb -s srv_epm1
Service name: srv_epm1
Service is enabled
Server pool: epmdb_srv_epm1
Cardinality: 1
Disconnect: false
Service role: PRIMARY
Management policy: AUTOMATIC
DTP transaction: false
AQ HA notifications: false
Failover type: SELECT
Failover method: BASIC
TAF failover retries: 180
TAF failover delay: 5
Connection Load Balancing Goal: LONG
Runtime Load Balancing Goal: NONE
TAF policy specification: BASIC
Edition:
Preferred instances: epmdb1
Available instances: epmdb2


tnsnames.ora的连接配置如下


epmdb_scan_taf =
(DESCRIPTION =
(LOAD_BALANCE = NO)
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.4.124.230)(PORT = 1521))
(CONNECT_DATA =
(SERVICE_NAME = srv_epm1)
)
)

由于服务只运行于epmdb1，因此必定连接epmdb1实例

sqlplus system/oracle@epmdb_scan_taf

SQL*Plus: Release 10.2.0.1.0 - Production on 星期四 6月 14 16:21:42 2012

Copyright (c) 1982, 2005, Oracle. All rights reserved.


连接到:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management,
OLAP,
Data Mining and Real Application Testing options

SQL> select instance_name from v$instance;

INSTANCE_NAME
----------------
epmdb1


数据库实例EPMDB1 down后，service发生了切换，再次连接数据库，已经运行于instane 2 .
sys@EPMDB1(10.4.124.233)> shutdown immediate;

[grid@dtydb3 ~]$ srvctl status service -d epmdb -s srv_epm1
Service srv_epm1 is running on instance(s) epmdb2



SQL> select instance_name from v$instance;

INSTANCE_NAME
----------------
epmdb1

SQL> /

INSTANCE_NAME
----------------
epmdb2