Oracle 10g RAC的负载均衡配置
一、客户端负载均衡的配置
1、当前服务器中的数据库版本如下:
SQL> select * from v$version;
BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod
PL/SQL Release 10.2.0.1.0 - Production
CORE 10.2.0.1.0 Production
TNS for Linux: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production
2、在客户端的tnsnames.ora的配置中,只要连接的是整个数据库的服务名,不是实例名。
在服务器端查看RAC数据库的service_names:
SQL> show parameter service_names
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
service_names string RACDB.chenxu.yo2.cn
SQL>
3、在客户端配置TNS:
客户端的负载均衡配置相对简单,只需要在tnsnames.ora中添加LOAD_BALANCE=ON这么一个选项即可。
RACDB =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.170)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.171)(PORT = 1521))
(LOAD_BALANCE = on)
)
(CONNECT_DATA =
(SERVICE_NAME = racdb.chenxu.yo2.cn)
)
)
配置TNS中的HOST值是服务器端RAC配置中的虚拟IP即VIP,如下:
[root@NODE01 admin]# more /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost
::1 localhost6.localdomain6 localhost6
192.168.1.180 node01
192.168.1.181 node02
192.168.1.170 vip01
192.168.1.171 vip02
10.10.10.1 priv01
10.10.10.2 priv02
4、在客户端测试:
开启sqlplus_1:
SQL> conn sys/chenxu@racdb as sysdba
已连接。
SQL>
SQL> show parameter instance_name
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
instance_name string RACDB2
SQL>
SQL> select instance_name from gv$instance;
INSTANCE_NAME
----------------
RACDB1
RACDB2
开启sqlplus_2:
SQL> conn sys/chenxu@racdb as sysdba
已连接。
SQL> show parameter instance_name
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
instance_name string RACDB1
开启sqlplus_3:
SQL> conn sys/chenxu@racdb as sysdba
已连接。
SQL>
SQL> show parameter instance_name
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
instance_name string RACDB2
开启sqlplus_4:
SQL> conn sys/chenxu@racdb as sysdba
已连接。
SQL> show parameter instance_name
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
instance_name string RACDB1
5、总结
这样当客户端连接RAC数据库时,会随机在TNS里面挑个监听地址进行连接。在Oracle 10g以前,假如有节点宕机或者类似事故时,客户端可能还是选择连接到这个节点,这样会发生较长时间的TCP等待超时。而在10g以后,由于VIP和FAN的引入,这样的情况可以得到很大程度的改善。客户端的负载均衡在通常情况下能够较好地工作,但是由于连接是在客户端随机发起的,这样客户端并不知道RAC各节点的负荷及连接数情况,有可能负荷大的节点还会源源不断地增加新的连接,导致RAC节点无法均衡工作。
二、服务器端负载均衡的配置
从Oracle 10g开始,服务器端的负载均衡可以根据RAC中各节点的负荷及连接数情况,而判定将新的客户端连接分配到负荷最小的节点上去。RAC中各节点的PMON进程每3秒会将各自节点的负荷(包括LOAD、最大LOAD、CPU使用率)及连接数更新到service_register里面,然后假如节点的负荷有发生变化,将会通知到监听程序,由监听程序再决定新的客户端连接分配至哪个节点。假如RAC中一个节点的监听失败了,PMON每一分钟会去检查一次是否已经恢复正常。
服务器端的监听配置是在各节点的tnsnames.ora里面添加一个连接到各个节点监听的条目,然后再在初始化参数里面设置remote_listeners这个参数。
1、测试客户端的TNS
修改客户端tnsnames.ora的文件,内容如下:
RACDB =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.170)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = racdb.chenxu.yo2.cn)
)
)
测试连接:
SQL> conn sys/chenxu@racdb as sysdba
已连接。
SQL>
SQL> show parameter instance_name
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
instance_name string RACDB1
2、配置服务器端TNS
服务器端的监听配置是在各节点的tnsnames.ora里面添加一个连接到各个节点监听的条目(红色代码),在服务器端每个节点的tnsnames.ora里面的内容如下:
[root@NODE01 admin]# pwd
/orac/orahome/oracle/product/10.2.0/db_1/network/admin
[root@NODE01 admin]#
[root@NODE01 admin]# more tnsnames.ora
# tnsnames.ora Network Configuration File: /orac/orahome/oracle/product/10.2.0/db_1/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.
RACDB1 =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = vip01)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = RACDB.chenxu.yo2.cn)
(INSTANCE_NAME = RACDB1)
)
)
RACDB =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = vip01)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = vip02)(PORT = 1521))
(LOAD_BALANCE = yes)
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = RACDB.chenxu.yo2.cn)
)
)
LISTENERS_RACDB =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = vip01)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = vip02)(PORT = 1521))
)
RACDB2 =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = vip02)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = RACDB.chenxu.yo2.cn)
(INSTANCE_NAME = RACDB2)
)
)
3、在初始化参数中设置参数remote_listeners
SQL> conn sys/chenxu@racdb as sysdba
已连接。
SQL> show parameter remote_listener
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
remote_listener string
SQL>
SQL> alter system set remote_listener='LISTENERS_RACDB' sid='*';
#(reset命令可以撤销设置,恢复默认值)
系统已更改。
SQL>
SQL> show parameter remote_listener
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
remote_listener string LISTENERS_RACDB
正确配置参数后,通过lsnrctl status命令看到在监听启动以后,可以看到监听器上有2个instance。
[root@NODE01 bin]# lsnrctl status
LSNRCTL for Linux: Version 10.2.0.1.0 - Production on 18-DEC-2008 05:40:08
Copyright (c) 1991, 2005, Oracle. All rights reserved.
Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
STATUS of the LISTENER
------------------------
Alias LISTENER_NODE01
Version TNSLSNR for Linux: Version 10.2.0.1.0 - Production
Start Date 18-DEC-2008 00:18:07
Uptime 0 days 5 hr. 22 min. 1 sec
Trace Level off
Security ON: Local OS Authentication
SNMP OFF
Listener Parameter File /orac/orahome/oracle/product/10.2.0/db_1/network/admin/listener.ora
Listener Log File /orac/orahome/oracle/product/10.2.0/db_1/network/log/listener_node01.log
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.1.170)(PORT=1521)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.1.180)(PORT=1521)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC)))
Services Summary...
Service "+ASM" has 1 instance(s).
Instance "+ASM1", status BLOCKED, has 1 handler(s) for this service...
Service "+ASM_XPT" has 1 instance(s).
Instance "+ASM1", status BLOCKED, has 1 handler(s) for this service...
Service "RACDB.chenxu.yo2.cn" has 2 instance(s).
Instance "RACDB1", status READY, has 2 handler(s) for this service...
Instance "RACDB2", status READY, has 1 handler(s) for this service...
Service "RACDBXDB.chenxu.yo2.cn" has 2 instance(s).
Instance "RACDB1", status READY, has 1 handler(s) for this service...
Instance "RACDB2", status READY, has 1 handler(s) for this service...
Service "RACDB_XPT.chenxu.yo2.cn" has 2 instance(s).
Instance "RACDB1", status READY, has 2 handler(s) for this service...
Instance "RACDB2", status READY, has 1 handler(s) for this service...
The command completed successfully
这时在客户端用sqlplus连接服务器数据库可能会出现如下错误:
ERROR:
ORA-12545: 因目标主机或对象不存在,连接失败
4、解决ORA-12545连接失败问题
方法一、配置客户端的Hosts文件
通过在客户端的Hosts文件中加入对两个服务名的名字解析可以解决ORA-12545问题。在windows下Hosts文件在C:"WINDOWS"system32"drivers"etc目录下,在linux修改/etc/hosts文件的内容。添加如下内容:
192.168.1.170 node01
192.168.1.171 node02
其中node01、node02为服务器节点的主机名。
[root@NODE01 bin]# hostname
NODE01
方法二、配置参数local_listener
这边就不详细描述,具体参考论坛文章,网址如下:(http://www.itpub.net/viewthread.php?tid=1060068)
5、通过客户端测试负载均衡
开启sqlplus_1:
SQL> conn sys/chenxu@racdb as sysdba
已连接。
SQL> show parameter instance_name
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
instance_name string RACDB1
开启sqlplus_2:
SQL> conn sys/chenxu@racdb as sysdba
已连接。
SQL> show parameter instance_name
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
instance_name string RACDB2
可以看到客户端能够连接到实例RACDB2,说明基于服务器端的负载均衡配置成功。