Oracle RAC 服务器端连接负载均衡(Load Balance)

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Oracle RAC服务器端的负载均衡是根据RAC中各节点的连接负荷数情况，将新的连接请求分配到负荷最小的节点上去。当数据库处于运行时，RAC中各节点的PMON进程每3秒会将各自节点的连接负荷数更新到service_register。而对于节点中任意监听器故障或监听器意外失败时，PMON进程会每1秒钟检查当前节点上的监听是否重启，以获得最新的负载信息来及时调整负载均衡。本文主要演示SUSE 10 + oracle 10g rac下的服务器端的负载均衡。

有关客户端的负载均衡可参考

一、服务器端负载均衡配置

1、为tnsnames.ora 添加相应的网络服务名(每个节点配置)
  oracle@bo2dbp:~> more $ORACLE_HOME/network/admin/tnsnames.ora
  # tnsnames.ora Network Configuration File: /u01/oracle/db/network/admin/tnsnames.ora
  # Generated by Oracle configuration tools.
   
  remote_lsnr_gobo4 =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.7.61)(PORT = 1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.7.62)(PORT = 1521))
    )
   
  local_lsnr_gobo4a =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.7.61)(PORT = 1521))
    )
   
  local_lsnr_gobo4b =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.7.62)(PORT = 1521))
    )
     
2、设置remote_listener参数
  alter system set remote_listener='<net_service_name>' scope=both sid='*';
   
  SQL> show parameter instance_name
   
  NAME                                 TYPE        VALUE
  ------------------------------------ ----------- ------------------------------  
  instance_name                        string      GOBO4A
  SQL> show parameter listener
   
  NAME                                 TYPE        VALUE
  ------------------------------------ ----------- ------------------------------  
  local_listener                       string
  remote_listener                      string
   
  SQL> alter system set remote_listener='remote_lsnr_gobo4' scope=both sid='*';
   
  System altered.

3、配置客户端tnsnames.ora
  -->客户端为suse 10  
  SZDB:~ # ifconfig eth1 | grep "inet addr"|cut -d " " -f12|cut -d : -f2  #--客户端主机的ip  
  192.168.7.2
  SZDB:~ # su - oracle
  oracle@SZDB:~> tail -10 $ORACLE_HOME/network/admin/tnsnames.ora
  GOBO4 =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.7.61)(PORT = 1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.7.62)(PORT = 1521))
      (LOAD_BALANCE = off)   #--由于仅仅测试寄予服务器端的负载均衡，因此关闭客户端负载均衡选项  
      (CONNECT_DATA =
        (SERVER = DEDICATED)
        (SERVICE_NAME = GOBO4)
      )
    )
  #Author : Robinson Cheng
  #Blog :   http://blog.csdn.net/robinson_0612   
   
4、检查监听情况
  oracle@bo2dbp:~> lsnrctl status
  Listening Endpoints Summary...
    (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.7.61)(PORT=1521)))
    (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.7.51)(PORT=1521)))
  Services Summary...
  Service "+ASM" has 1 instance(s).
    Instance "+ASM1", status BLOCKED, has 1 handler(s) for this service...
  Service "GOBO4" has 2 instance(s).
    Instance "GOBO4A", status READY, has 2 handler(s) for this service...
    Instance "GOBO4B", status READY, has 1 handler(s) for this service..
  .......
   
  oracle@bo2dbs:~> lsnrctl status
  Listening Endpoints Summary...
    (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.7.62)(PORT=1521)))
    (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.7.52)(PORT=1521)))
  Services Summary...
  Service "+ASM" has 1 instance(s).
    Instance "+ASM2", status BLOCKED, has 1 handler(s) for this service...
  Service "GOBO4" has 2 instance(s).
    Instance "GOBO4A", status READY, has 1 handler(s) for this service...
    Instance "GOBO4B", status READY, has 2 handler(s) for this service...
  ..........

  #--如果监听或数据库需要重启异常请考虑重新启动监听器或数据库  
  #--下面清空监听日志以便于后续统计连接信息  
  oracle@bo2dbp:/u01/oracle/db/network/log> cat /dev/null>listener_bo2dbp.log
  oracle@bo2dbs:/u01/oracle/db/network/log> cat /dev/null>listener_bo2dbs.log