日期:2014-05-16 浏览次数:20628 次
Rac环境安装完成之后,打算简单测试一下Oracle RAC的负载均衡功能。 配置负载均衡,需要在客户端的tnsnames.ora中进行配置。 TESTRAC = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 172.25.198.224)(PORT = 1521)) (ADDRESS = (PROTOCOL = TCP)(HOST = 172.25.198.225)(PORT = 1521)) (LOAD_BALANCE = yes) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = testrac) ) ) 设置了LOAD_BALANCE = yes之后,使用TESTRAC服务名连接数据库时就启动了负载均衡功能。 登陆RAC实例,检查两个实例上的会话连接情况: SQL> SELECT INST_ID, COUNT(*) FROM GV$SESSION GROUP BY INST_ID; INST_ID COUNT(*) ---------- ---------- 1 31 2 31 下面在客户端连接RAC实例,并检查当前连接的是哪个实例: SQL> CONN NDMAIN@TESTRAC输入口令: ******已连接。 SQL> SELECT INSTANCE_NAME FROM V$INSTANCE; INSTANCE_NAME ---------------- testrac1 SQL> CONN NDMAIN@TESTRAC输入口令: ******已连接。 SQL> SELECT INSTANCE_NAME FROM V$INSTANCE; INSTANCE_NAME ---------------- testrac2 由于两个实例上会话数量相当,所以Oracle在分配连接时,分配给每个实例的概率基本相同。 这是会话连接两次的情况,下面看看当多个会话连接时,Oracle是如何分配的。 SQL> DISC从 Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bit Production With the Partitioning, Real Application Clusters, OLAP and Data Mining options 断开 首先断开刚才连接的会话,然后启动4个新的连接,并检查这些连接分布到哪些实例上: E:>SQLPLUS NDMAIN/NDMAIN@TESTRAC SQL*Plus: Release 10.2.0.1.0 - Production on 星期四 3月 22 19:15:26 2007 Copyright (c) 1982, 2005, Oracle. All rights reserved. 连接到: Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bit Production With the Partitioning, Real Application Clusters, OLAP and Data Mining options SQL> SELECT INSTANCE_NAME FROM V$INSTANCE; INSTANCE_NAME ---------------- testrac1 SQL> HOST Microsoft Windows 2000 [Version 5.00.2195] (C) 版权所有 1985-2000 Microsoft Corp. E:>SQLPLUS NDMAIN/NDMAIN@TESTRAC SQL*Plus: Release 10.2.0.1.0 - Production on 星期四 3月 22 19:15:46 2007 Copyright (c) 1982, 2005, Oracle. All rights reserved. 连接到: Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bit Production With the Partitioning, Real Application Clusters, OLAP and Data Mining options SQL> SELECT INSTANCE_NAME FROM V$INSTANCE; INSTANCE_NAME ---------------- testrac1 SQL> HOST Microsoft Windows 2000 [Version 5.00.2195] (C) 版权所有 1985-2000 Microsoft Corp. E:>SQLPLUS NDMAIN/NDMAIN@TESTRAC SQL*Plus: Release 10.2.0.1.0 - Production on 星期四 3月 22 19:16:02 2007 Copyright (c) 1982, 2005, Oracle. All rights reserved. 连接到: Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bit Production With the Partitioning, Real Application Clusters, OLAP and Data Mining options SQL> SELECT INSTANCE_NAME FROM V$INSTANCE; INSTANCE_NAME ---------------- testrac2 SQL> HOST Microsoft Windows 2000 [Version 5.00.2195] (C) 版权所有 1985-2000 Microsoft Corp. E:>SQLPLUS NDMAIN/NDMAIN@TESTRAC SQL*Plus: Release 10.2.0.1.0 - Production on 星期四 3月 22 19:16:16 2007 Copyright (c) 1982, 2005, Oracle. All rights reserved. 连接到: Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bit Production With the Partitioning, Real Application Clusters, OLAP and Data Mining options SQL> SELECT INSTANCE_NAME FROM V$INSTANCE; INSTANCE_NAME ---------------- testrac2 可以看到,由于两个实例负载相当,Oracle基本上是按照50%的概率给每个实例分配新的连接。 |
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