RAC負載均衡的簡單測試（二）
Rac環境安裝完成之後，打算簡單測試一下Oracle RAC的負載均衡功能。
這篇繼續討論負載均衡的特性。
RAC負載均衡的簡單測試（一）：http://yangtingkun.itpub.net/post/468/279433
上一篇的測試中可以看到，當兩個例項的負載相當的時候，新連線會平均分配到兩個例項上去。
下面看看如果其中一個例項的連線數明顯大於另一個例項的情況。增加連線TESTRAC2例項的連線數，這裡使用的方法是在racnode2資料庫上使用直接連線的方式：
$ sqlplus ndmain
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 19:24:23 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
輸入口令:
連線到:
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> host
$ sqlplus ndmain
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 19:24:28 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
輸入口令:
連線到:
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> host
$ sqlplus ndmain
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 19:24:33 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
輸入口令:
連線到:
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> host
$ sqlplus ndmain
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 19:24:37 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
輸入口令:
連線到:
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> host
$ sqlplus ndmain
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 19:24:44 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
輸入口令:
連線到:
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> host
$ sqlplus ndmain
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 19:24:48 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
輸入口令:
連線到:
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> host
$ sqlplus ndmain
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 19:24:54 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
輸入口令:
連線到:
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> host
$ sqlplus ndmain
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 19:25:00 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
輸入口令:
連線到:
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>
查詢目前資料庫的連線情況：
SQL> SELECT INST_ID, COUNT(*) FROM GV$SESSION GROUP BY INST_ID;
INST_ID COUNT(*)
---------- ----------
1 31
2 38
下面嘗試多次連線，並檢查連線的例項：
SQL> CONN NDMAIN/NDMAIN@TESTRAC已連線。
SQL> SELECT INSTANCE_NAME FROM V$INSTANCE;
INSTANCE_NAME
----------------
testrac2
SQL> CONN NDMAIN/NDMAIN@TESTRAC已連線。
SQL> SELECT INSTANCE_NAME FROM V$INSTANCE;
INSTANCE_NAME
----------------
testrac1
SQL> CONN NDMAIN/NDMAIN@TESTRAC已連線。
SQL> SELECT INSTANCE_NAME FROM V$INSTANCE;
INSTANCE_NAME
----------------
testrac2
SQL> CONN NDMAIN/NDMAIN@TESTRAC已連線。
SQL> SELECT INSTANCE_NAME FROM V$INSTANCE;
INSTANCE_NAME
----------------
testrac1
SQL> CONN NDMAIN/NDMAIN@TESTRAC已連線。
SQL> SELECT INSTANCE_NAME FROM V$INSTANCE;
INSTANCE_NAME
----------------
testrac2
發現連線到兩個例項的機率仍然是一樣的。看看連續啟動多個連線的情況：
E:>SQLPLUS NDMAIN/NDMAIN@TESTRAC
SQL*Plus: Release 10.2.0.1.0 - Production on 星期四 3月 22 19:27:05 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
連線到:
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$INSTANCE;
INSTANCE_NAME
----------------
testrac1
SQL> HOST
Microsoft Windows 2000 [Version 5.00.2195]
(C) 版權所有 1985-2000 Microsoft Corp.
E:>SQLPLUS NDMAIN/NDMAIN@TESTRAC
SQL*Plus: Release 10.2.0.1.0 - Production on 星期四 3月 22 19:27:18 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
連線到:
Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, OLAP and Data Mining options
SQL> SELECT INSTANCE_NAME FROM V$INSTANCE;
INSTANCE_NAME
----------------
testrac2
SQL> HOST
Microsoft Windows 2000 [Version 5.00.2195]
(C) 版權所有 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 19:27:31 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
連線到:
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$INSTANCE;
INSTANCE_NAME
----------------
testrac1
SQL> HOST
Microsoft Windows 2000 [Version 5.00.2195]
(C) 版權所有 1985-2000 Microsoft Corp.
E:>SQLPLUS NDMAIN/NDMAIN@TESTRAC
SQL*Plus: Release 10.2.0.1.0 - Production on 星期四 3月 22 19:27:40 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
連線到:
Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, OLAP and Data Mining options
SQL> SELECT INSTANCE_NAME FROM V$INSTANCE;
INSTANCE_NAME
----------------
testrac2
可以看到，結果仍然是50%的機率。難道負載均衡不考慮例項本身的負載，只是對新增連線進行平均分配？
其實並不是這樣，關鍵在於負載均衡的功能是透過LISTENER來實現的。而在上面增加TESTRAC2上的連線數的時候，採用的是本地連線方式，恰恰繞過了LISTENER，對於LISTENER來說，這些新增的會話都是不可見的。因此，得到的結果當然和原來的一致。
下面斷開剛才連線的所有會話：
SQL> SELECT INST_ID, COUNT(*) FROM GV$SESSION GROUP BY INST_ID;
INST_ID COUNT(*)
---------- ----------
1 31
2 30
然後以TESTRAC2為服務名，連線到RAC的TESTRAC2例項上：
$ sqlplus ndmain/ndmain@testrac2
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 21:14:44 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
連線到:
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> host
$ sqlplus ndmain/ndmain@testrac2
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 21:14:52 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
連線到:
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> host
$ sqlplus ndmain/ndmain@testrac2
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 21:14:55 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
連線到:
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> host
$ sqlplus ndmain/ndmain@testrac2
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 21:14:59 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
連線到:
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> host
$ sqlplus ndmain/ndmain@testrac2
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 21:15:04 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
連線到:
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> host
$ sqlplus ndmain/ndmain@testrac2
SQL*Plus: Release 10.2.0.2.0 - Production on 星期四 3月 22 21:15:14 2007
Copyright (c) 1982, 2005, Oracle. All Rights Reserved.
連線到:
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>
再次測試連線例項的情況：
SQL> SELECT INST_ID, COUNT(*) FROM GV$SESSION GROUP BY INST_ID;
INST_ID COUNT(*)
---------- ----------
1 31
2 36
SQL> CONN NDMAIN/NDMAIN@TESTRAC已連線。
SQL> SELECT INSTANCE_NAME FROM V$INSTANCE;
INSTANCE_NAME
----------------
testrac1
SQL> CONN NDMAIN/NDMAIN@TESTRAC已連線。
SQL> SELECT INSTANCE_NAME FROM V$INSTANCE;
INSTANCE_NAME
----------------
testrac1
SQL> CONN NDMAIN/NDMAIN@TESTRAC已連線。
SQL> SELECT INSTANCE_NAME FROM V$INSTANCE;
INSTANCE_NAME
----------------
testrac1
SQL> DISC從 Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, OLAP and Data Mining options 斷開
可以看到，連線時Oracle都會將會話連線到TESTRAC1上。下面看看連續啟動多個會話，Oracle如何在例項間分配會話：
E:>SQLPLUS NDMAIN/NDMAIN@TESTRAC
SQL*Plus: Release 10.2.0.1.0 - Production on 星期四 3月 22 21:19:41 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
連線到:
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$INSTANCE;
INSTANCE_NAME
----------------
testrac1
SQL> HOST
Microsoft Windows 2000 [Version 5.00.2195]
(C) 版權所有 1985-2000 Microsoft Corp.
E:>SQLPLUS NDMAIN/NDMAIN@TESTRAC
SQL*Plus: Release 10.2.0.1.0 - Production on 星期四 3月 22 21:19:59 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
連線到:
Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, OLAP and Data Mining options
SQL> SELECT INSTANCE_NAME FROM V$INSTANCE;
INSTANCE_NAME
----------------
testrac1
SQL> HOST
Microsoft Windows 2000 [Version 5.00.2195]
(C) 版權所有 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 21:20:12 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
連線到:
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>
根據上面的測試可以看出，Oracle的負載均衡和例項透過LISTENER建立的連線數有關。
來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/4227/viewspace-69237/，如需轉載，請註明出處，否則將追究法律責任。
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