TNSNAMES.ORA 配置
上面的sqlnet.ora文件说明：SQLNET.AUTHENTICATION_SERVICES= (NTS)——这个表示采用os认证，在数据库服务器上，可以利用sqlplus “/ as sysdba”。一般这个配置在windows上是ok的，在unix环境下可能会有问题，一般在unix下可以去掉这个配置。NAMES.DIRECTORY_PATH= (TNSNAMES, HOSTNAME, ONAMES)——表示将首先利用tnsnames进行解析；如果tnsnames解析不到，将使用hostname解析；如果hostname解析不 到，将采用onames进行解析。被注释掉的NAMES.DEFAULT_DOMAIN = us.oracle.com——表示采用默认的domain name为us.oracle.com，在tnsnames.ora中如果配置对应的解析，如果原来的别名oralocal，那么，当启用这个参数后，在 tnsnames中的配置要改成oralocal.us.oracle.com。在使用tnsping时或者sqlplus登录时，只需写前面的别名，系 统会自动加上后面的domain name来进行解析。检查完毕sqlnet.ora，一般都会发现是使用tnsname来解析别名的，那么，tnsnames.ora中可以有哪些配置种类呢？# TNSNAMES.ORA Network Configuration File: $ORACLE_HOME/NETWORK/ADMIN/tnsnames.ora# Generated by Oracle configuration tools.###### 一般的配置 ##################################ORALOCAL = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1521)) ) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = oralocal) ) )###### 这样也行，用SID=oralocal ###########################ORALOCAL_2 = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1521)) ) (CONNECT_DATA = (SERVER = DEDICATED) (SID = oralocal) )###### RAC的配置(3节点rac) ###############################ORALOCAL = (DESCRIPTION = (load_balance = yes) (failover = on) (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.1)(PORT = 1521)) (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.2)(PORT = 1521)) (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.3)(PORT = 1521)) ) (CONNECT_DATA = (SERVICE_NAME = oralocal) (SERVER = DEDICATED) (failover_mode=(type=select)(method=basic)(retries=20)(delay=20)) ) ) ORALOCAL_NODE1 = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.1)(PORT = 1521)) ) (CONNECT_DATA = (SERVICE_NAME = oralocal) (INSTANCE_NAME = oralocal_node1) ) )ORALOCAL_NODE2= (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.2)(PORT = 1521)) ) (CONNECT_DATA = (SERVICE_NAME = oralocal) (INSTANCE_NAME = oralocal_node2) ) ) ORALOCAL_NODE3 = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.3)(PORT = 1521)) ) (CONNECT_DATA = (SERVICE_NAME = oralocal) (INSTANCE_NAME = oralocal_node3) ) ) )###### DATA GUARD配置（primary库和standby库都需要配置）##############standby = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.2.2)(PORT = 1521)) ) (CONNECT_DATA = (SERVER=DEDICATED) (SERVICE_NAME = oralocal) ) )primary = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.2.1)(PORT = 1521)) ) (CONNECT_DATA = (SERVER=DEDICATED) (SERVICE_NAME = oralocal) ) )另外需要注意的2点情况：（1）如果tnsnames中的service_name配置错误，配置成了instance_name了，这个时候会发生tnsping能通，但是 sqlplus连接不上的奇怪情况。报错ORA-12514: TNS:listener could not resolve SERVICE_NAME given in connect descriptor。这个时候查错的时候，需要检查对应的service_name。（2）如果远程数据库是rac，而且本地客户端端远程数据库处于不同的网段，通过公网链接，rac对外的ip映射只有一个，即只映射到一个节点。请注意在 客户端配置tnsnames的时候按照单机的情况来配置。呵呵，dba不仅仅要学习oracle，了解一些网络的知识，特别是自己系统的网络架构，也是需 要的。
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