ORACLE 10g RAC 負(fù)載均衡配置

負(fù)載均衡是指連接的負(fù)載均衡。RAC的負(fù)載均衡主要是指新會(huì)話連接到RAC數(shù)據(jù)庫(kù)時(shí)，如何判定這個(gè)新的連接要連到哪個(gè)節(jié)點(diǎn)進(jìn)行工作。在RAC中，負(fù)載均衡分為兩種，一種是基于客戶端連接的，另外一種是基于服務(wù)器端的。一、客戶端負(fù)載均衡的配置1、當(dāng)前服務(wù)器中的數(shù)據(jù)庫(kù)版本如下：SQL〉select*fromv$version;BANNEROracleDatabase10gEnterpriseEditionRelease.0-ProdPL/SQLRelease.0-ProductionCORE.0ProductionTNSforLinux:Version.0-ProductionNLSRTLVersion.0—Production2、在客戶端的tnsnames.ora的配置中，只要連接的是整個(gè)數(shù)據(jù)庫(kù)的服務(wù)名，不是實(shí)例名在服務(wù)器端查看RAC數(shù)據(jù)庫(kù)的service_names：SQL>showparameterservice_namesNAMETYPEVALUEservice_namesstringRACDB.SQL>3、在客戶端配置TNS：客戶端的負(fù)載均衡配置相對(duì)簡(jiǎn)單，只需要在tnsnames.ora中添加L0AD_BALANCE=0N這么一個(gè)選項(xiàng)即可。RACDB=

(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=70)(P0RT=1521))(ADDRESS=(PROTOCOL=TCP)(HOST=71)(P0RT=1521))(LOAD_BALANCE=on))(CONNECT_DATA=(SERVICE_NAME=)))配置TNS中的HOST值是服務(wù)器端RAC配置中的虛擬IP即VIP,如下：[root@NODE01admin]#more/etc/hostsDonotremovethefollowingline,orvariousprogramsthatrequirenetworkfunctionalitywillfail.localhost.localdomainlocalhost::1localhost6.localdomain6localhost61.180node011.181node021.170vip011.171vip02priv01priv024、在客戶端測(cè)試：開(kāi)啟sqlplus_1：SQL〉connsys/chenxu@racdbassysdba

已連接。SQL>SQL>showparameterinstance_nameNAMETYPEVALUEinstance_namestringRACDB2SQL〉SQL〉selectinstance_namefromgv$instance;INSTANCE_NAMERACDB1RACDB2開(kāi)啟sqlplus_2：SQL>connsys/chenxu@racdbassysdba已連接。SQL>showparameterinstance_nameNAMETYPEVALUEinstance_namestringRACDB1開(kāi)啟sqlplus_3：SQL>connsys/chenxu@racdbas已連接。SQL>sysdba

SQL〉showparameterNAMEinstance_nameTYPEVALUEinstance_namestringRACDB2開(kāi)啟sqlplus_4：SQL>connsys/chenxu@racdbassysdba已連接。SQL>showparameterinstance_nameNAMETYPEVALUEinstance_namestringRACDB15、總結(jié)這樣當(dāng)客戶端連接RAC數(shù)據(jù)庫(kù)時(shí)，會(huì)隨機(jī)在TNS里面挑個(gè)監(jiān)聽(tīng)地址進(jìn)行連接。在Oracle10g以前，假如有節(jié)點(diǎn)宕機(jī)或者類似事故時(shí)，客戶端可能還是選擇連接到這個(gè)節(jié)點(diǎn)，這樣會(huì)發(fā)生較長(zhǎng)時(shí)間的TCP等待超時(shí)。而在10g以后，由于VIP和FAN的引入，這樣的情況可以得到很大程度的改善?？蛻舳说呢?fù)載均衡在通常情況下能夠較好地工作，但是由于連接是在客戶端隨機(jī)發(fā)起的，這樣客戶端并不知道RAC各節(jié)點(diǎn)的負(fù)荷及連接數(shù)情況，有可能負(fù)荷大的節(jié)點(diǎn)還會(huì)源源不斷地增加新的連接，導(dǎo)致RAC節(jié)點(diǎn)無(wú)法均衡工作。二、服務(wù)器端負(fù)載均衡的配置從Oracle10g開(kāi)始，服務(wù)器端的負(fù)載均衡可以根據(jù)RAC中各節(jié)點(diǎn)的負(fù)荷及連接數(shù)情況，而判定將新的客戶端連接分配到負(fù)荷最小的節(jié)點(diǎn)上去。RAC中各節(jié)點(diǎn)的PMON進(jìn)程每3秒會(huì)將各自節(jié)點(diǎn)的負(fù)荷（包括LOAD、最大LOAD、CPU使用率）及連接數(shù)更新到service_register里面，然后假如節(jié)點(diǎn)的負(fù)荷有發(fā)生變化，將會(huì)通知到監(jiān)聽(tīng)程序，由監(jiān)聽(tīng)程序再?zèng)Q定新的客戶

端連接分配至哪個(gè)節(jié)點(diǎn)。假如RAC中一個(gè)節(jié)點(diǎn)的監(jiān)聽(tīng)失敗了，PMON每一分鐘會(huì)去檢查一次是否已經(jīng)恢復(fù)正常。服務(wù)器端的監(jiān)聽(tīng)配置是在各節(jié)點(diǎn)的tnsnames.ora里面添加一個(gè)連接到各個(gè)節(jié)點(diǎn)監(jiān)聽(tīng)的條目，然后再在初始化參數(shù)里面設(shè)置remote_listeners這個(gè)參數(shù)。1、測(cè)試客戶端的TNS修改客戶端tnsnames.ora的文件，內(nèi)容如下：RACDB=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=70)(P0RT=1521)))(CONNECT_DATA=(SERVICE_NAME=)))測(cè)試連接：SQL〉connsys/chenxu@racdbassysdba已連接。SQL>SQL>showparameterinstance_nameNAMETYPEVALUEinstance_namestringRACDB12、配置服務(wù)器端TNS

服務(wù)器端的監(jiān)聽(tīng)配置是在各節(jié)點(diǎn)的tnsnames.ora里面添加一個(gè)連接到各個(gè)節(jié)點(diǎn)監(jiān)聽(tīng)的條目(紅色代碼)，在服務(wù)器端每個(gè)節(jié)點(diǎn)的tnsnames.ora里面的內(nèi)容如下：[root@NODEOladmin]#pwd/orac/orahome/oracle/product/10.2.0/db_l/network/admin[root@NODE01admin]#[root@NODE01admin]#moretnsnames.oratnsnames.oraNetworkConfigurationFile:/orac/orahome/oracle/product/10.2.0/db_l/network/admin/tnsnames.oraGeneratedbyOracleconfigurationtools.RACDB1=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=vip01)(P0RT=1521))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=RACDB.)(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.)))LISTENERS_RACDB=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=vipOl)(PORT=1521))(ADDRESS=(PROTOCOL=TCP)(HOST=vip02)(P0RT=1521)))RACDB2=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=vip02)(PORT=1521))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=RACDB.)(INSTANCE_NAME=RACDB2)))3、在初始化參數(shù)中設(shè)置參數(shù)remote_listenersSQL>connsys/chenxu@racdbassysdba已連接。SQL>showparameterremote_listenerNAMETYPEVALUE

remote_listenerstringSQL〉SQL〉altersystemsetremote_listener二'LISTENERS_RACDB'sid二'*'#(reset命令可以撤銷設(shè)置，恢復(fù)默認(rèn)值)系統(tǒng)已更改。SQL〉SQL>showparameterremote_listenerNAMETYPEVALUEremote_listenerstringLISTENERS_RACDB正確配置參數(shù)后，通過(guò)lsnrctlstatus命令看到在監(jiān)聽(tīng)啟動(dòng)以后，可以看到監(jiān)聽(tīng)器上有2個(gè)instance。[root@NODE01bin]#lsnrctlstatusLSNRCTLforLinux:Version.0—Productionon18—DEC—200805:40:08Copyright(c)1991,2005,Oracle.Allrightsreserved.Connectingto(ADDRESS=(PR0T0C0L=tcp)(H0ST=)(P0RT=1521))STATUSoftheLISTENERAliasVersionLISTENERN0DE01AliasVersionTNSLSNRforLinux:Version.0—ProductionStartDateStartDate18—DEC—200800:18:07Uptime0days5hr.22min.1secTraceLeveloffSecurityON:LocalOSAuthenticationSNMPOFFListenerParameterFile/orac/orahome/oracle/product/10.2.0/db_1/network/admin/listener.oraListenerLogFile/orac/orahome/oracle/product/10.2.0/db_1/network/log/listener_node01.logListeningEndpointsSummary...(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(H0ST=70)(P0RT=1521)))(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(H0ST=80)(P0RT=1521)))(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC)))ServicesSummary...Service""+ASM""has1instance(s).Instance""+ASM1",statusBLOCKED,has1handler(s)forthisservice...Service""+ASM_XPT"has1instance(s).Instance""+ASM1",statusBLOCKED,has1handler(s)forthisservice...Service"RACDB."has2instance(s).Instance"RACDB1",statusREADY,has2handler(s)forthisservice...Instance"RACDB2",statusREADY,has1handler(s)forthisservice...Instance"RACDB1",statusREADY,has2handler(s)forthisservice...Instance"RACDB2",statusREADY,has1handler(s)forthisservice...Service""RACDBXDB.Service""RACDBXDB.""has2instance(s).Instance""RACDB1",statusREADY,has1handler(s)forthisservice...Instance""RACDB2",statusREADY,has1handler(s)forthisservice...Instance""RACDB1",statusREADY,has1handler(s)forthisservice...Instance""RACDB2",statusREADY,has1handler(s)forthisservice...Service""RACDB_XPT.""has2instance(s).Instance""RACDB1"",statusREADY,has2handler(s)forthisservice...Instance""RACDB2",statusREADY,has1handler(s)forthisservice...Thecommandcompletedsuccessfully這時(shí)在客戶端用sqlplus連接服務(wù)器數(shù)據(jù)庫(kù)可能會(huì)出現(xiàn)如下錯(cuò)誤：ERROR:ORA-12545:因目標(biāo)主機(jī)或?qū)ο蟛?/p>