Oracle RAC 服务器端连接负载均衡(Load Balance)

 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
      Oracle RAC 客户端连接负载均衡(Load Balance)
      配置RAC负载均衡与故障转移
 
有关Oracle 网络配置相关基础以及概念性的问题请参考：
        配置ORACLE 客户端连接到数据库 
        配置非默认端口的动态服务注册 
        配置sqlnet.ora限制IP访问Oracle 
       Oracle 监听器日志配置与管理 
       设置 Oracle 监听器密码(LISTENER)
       Oracle RAC 监听配置
       ORACLE RAC 下非缺省端口监听配置(listener.ora tnsnames.ora)

 

一、服务器端负载均衡配置

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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

  二、测试服务器端的负载均衡

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1、从客户端建立连接
  oracle@SZDB:~> more load_balance.sh
  #!/bin/bash
  for i in {1..1000}
  do
  echo $i
  sqlplus -S system/oracle@GOBO4 <<EOF
  select instance_name from v\$instance;
  EOF
  sleep 1
  done
  exit 0
  oracle@SZDB:~> ./load_balance.sh >srv_load_bal.log

2、分析监听日志
  oracle@bo2dbp:/u01/oracle/db/network/log> more listener_bo2dbp.log
  12-OCT-2012 12:00:10 * service_update * GOBO4B * 0   #节点bo2dbs上的实例GOBO4B的更新到bo2dbp上监听器的更新信息
  12-OCT-2012 12:00:35 * service_update * GOBO4B * 0
  12-OCT-2012 12:01:04 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=GOBO4)(CID=(PROGRAM=sqlplus@SZDB)(HOST=SZDB)
  (USER=oracle))) * (ADDRESS=(PROTOCOL=tcp)(HOST=192.168.7.2)(PORT=50322)) * establish * GOBO4 * 0
  12-OCT-2012 12:01:05 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=GOBO4)(CID=(PROGRAM=sqlplus@SZDB)(HOST=SZDB)
  (USER=oracle))) * (ADDRESS=(PROTOCOL=tcp)(HOST=192.168.7.2)(PORT=50325)) * establish * GOBO4 * 0
  12-OCT-2012 12:01:07 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=GOBO4)(CID=(PROGRAM=sqlplus@SZDB)(HOST=SZDB)
  (USER=oracle))) * (ADDRESS=(PROTOCOL=tcp)(HOST=192.168.7.2)(PORT=50328)) * establish * GOBO4 * 0
  12-OCT-2012 12:01:08 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=GOBO4)(CID=(PROGRAM=sqlplus@SZDB)(HOST=SZDB)
  (USER=oracle))) * (ADDRESS=(PROTOCOL=tcp)(HOST=192.168.7.2)(PORT=50330)) * establish * GOBO4 * 0

  #上面的日志片断中可以看出全部是客户端发起的到bo2dbp节点上的建立连接的信息

  #下面来查看bo2dbs上的监听日志
  oracle@bo2dbs:/u01/oracle/db/network/log> more listener_bo2dbs.log
  12-OCT-2012 12:00:10 * service_update * GOBO4B * 0
  12-OCT-2012 12:00:10 * service_update * GOBO4B * 0
  12-OCT-2012 12:00:14 * (CONNECT_DATA=(CID=(PROGRAM=)(HOST=bo2dbs)(USER=oracle))(COMMAND=status)(ARGUMENTS=64)
  (SERVICE=LISTENER_BO2DBS)(VERSION=169870080)) * status * 0
  12-OCT-2012 12:00:35 * service_update * GOBO4B * 0
  12-OCT-2012 12:00:35 * service_update * GOBO4B * 0
  12-OCT-2012 12:01:04 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=GOBO4)(CID=(PROGRAM=sqlplus@SZDB)(HOST=SZDB)
  (USER=oracle))(INSTANCE_NAME=GOBO4B)) * (ADDRESS=(PROTOCOL=tcp)(HOST=192.168.7.2)(PORT=61862)) * establish * GOBO4 * 0
  12-OCT-2012 12:01:07 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=GOBO4)(CID=(PROGRAM=sqlplus@SZDB)(HOST=SZDB)
  (USER=oracle))(INSTANCE_NAME=GOBO4B)) * (ADDRESS=(PROTOCOL=tcp)(HOST=192.168.7.2)(PORT=61868)) * establish * GOBO4 * 0
  12-OCT-2012 12:01:09 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=GOBO4)(CID=(PROGRAM=sqlplus@SZDB)(HOST=SZDB)
  (USER=oracle))(INSTANCE_NAME=GOBO4B)) * (ADDRESS=(PROTOCOL=tcp)(HOST=192.168.7.2)(PORT=61872)) * establish * GOBO4 * 0

  #在12-OCT-2012 12:01:04时刻，连接信息中有INSTANCE_NAME=GOBO4B的连接信息，而节点bo2dbp上也有一条类似的信息，因此该条连接
  #日志是由节点bo2dbp转发过来而建立的连接请求。
  #同样在12-OCT-2012 12:01:07时刻，节点bo2dbp转发过来而建立的连接请求。

  #小结一下，
  #对于直接连接，监听器日志中将出现establish，且不含有INSTANCE_NAME=GOBO4B 字样
  #而对于转发的连接，则转发节点与接收的节点同时存在连接信息，转发节点上存在连接信息的与普通的连接请求一样，
  #而接收的节点上存在INSTANCE_NAME=<instance_name> 信息

3、检查负载均衡结果
  oracle@SZDB:~> grep GOBO4A srv_load_bal.log |wc -l
  755
  oracle@SZDB:~> grep GOBO4B srv_load_bal.log |wc -l
  245
  #从上面的日志文件中可知总共有755个客户端连接到了gobo4a，有245各客户端连接到了gobo4b

  #下面查看监听器日志来获得连接信息
  #下面的查询中在节点bo2dbp上总共有接受了1000个用户连接
  oracle@bo2dbp:/u01/oracle/db/network/log> grep establish listener_bo2dbp.log |wc -l
  1000

  #下面的查询查看是否有从节点bo2dbs转发过来的连接，结果为0，说明没有任何连接请求从bo2dbs转发过来
  oracle@bo2dbp:/u01/oracle/db/network/log> grep INSTANCE_NAME=GOBO4 listener_bo2dbp.log |wc -l
  0

  #接下来查看节点bo2dbs的监听日志，可以看出总共接受了245个连接请求
  oracle@bo2dbs:/u01/oracle/db/network/log> grep establish listener_bo2dbs.log |wc -l
  245

  #下面的过滤情况也表明在节点bo2dbs上的连接是从bo2dbp上转发的连接，而非客户端直接到bo2dbs的请求连接
  oracle@bo2dbs:/u01/oracle/db/network/log> grep INSTANCE_NAME=GOBO4 listener_bo2dbs.log |wc -l
  245

  #从监听器的日志检查可以，测试中的连接全部请求到节点bo2dbp，是由于tnsnames.ora中ADDRESS的第一个IP地址就是bo2dbp的IP
  #因此所有的连接都是请求到bo2dbp，而没有客户端发出到bo2dbs的连接请求
  #其次是尽管在bo2dbp有1000个连接请求，而真正建立连接的只有755个，有245转发到了节点bo2dbs

三、总结
      1、服务器端的负载均衡需要配置remote_listener参数，而该参数的值依赖于tnsnames.ora的连接字符串
      2、对于基于服务器端的连接负载均衡，监听器会根据当前节点、实例上的连接负载情况进行转发到空闲的实例
      3、转发的依据仅仅是当前节点监听的连接数量的多少，而非当前实例的过度负载
      4、从上面的测试可以得出，各个节点的连接并不算均衡，是相对的均衡，因此应结合客户端连接负载协同工作
      5、对于当前实例的过度负载的情形，应结合配置service方法来实现负载均衡