Oracle11gR2Grid Infrastructure (CRS)中引入了Single Client Access Name (SCAN)来简化客户端对数据库服务的访问。

本文将详细介绍如何配置 DNS来解析 SCAN VIP

 

演示环境

OracleEnterprise Linux 5.6

 

一、安装 DNS Server

 

rpm -ivhbind-9.3.6-16.P1.el5.i386.rpm

rpm -ivhbind-chroot-9.3.6-16.P1.el5.i386.rpm

rpm -ivhcaching-nameserver-9.3.6-16.P1.el5.i386.rpm

 

DNS的守护进程

/usr/sbin/named   

/usr/sbin/rndc

DNS的脚本

/etc/init.d/named

DNS的端口

53       953(tcp udp) 

DNS的配置文件

/var/named/chroot/etc/named.conf(主配置文件)  

/var/named/chroot/*

 

二、配置 DNS Server

1、创建主配置文件 named.conf

[root@rac1 Server]#cd /var/named/chroot/etc

[root@rac1 etc]# ls-lt

total 24

-rw-r----- 1 rootnamed  113 Jun  1 07:46 rndc.key

-rw-r----- 1 rootnamed 1230 Jan 14  2011named.caching-nameserver.conf

-rw-r----- 1 rootnamed  955 Jan 14  2011 named.rfc1912.zones

-rw-r--r-- 1 rootroot  3519 Feb 27  2006 localtime

 

[root@rac1 etc]#more named.caching-nameserver.conf

//

//named.caching-nameserver.conf

//

// Provided by RedHat caching-nameserver package to configure the

// ISC BIND named(8)DNS server as a caching only nameserver

// (as a localhostDNS resolver only).

//

// See/usr/share/doc/bind*/sample/ for example named configuration files.

//

// DONOT EDIT THIS FILE - use system-config-bind or an editor

// tocreate named.conf - edits to this file will be lost on

// caching-nameserver package upgrade.

//

 

------创建 named.conf配置文件

[root@rac1 etc]# cp-p named.caching-nameserver.conf named.conf

[root@rac1 etc]# ls-lt

total 28

-rw-r----- 1 rootnamed  113 Jun  1 07:46 rndc.key

-rw-r----- 1 rootnamed 1230 Jan 14  2011named.caching-nameserver.conf

-rw-r----- 1 rootnamed 1230 Jan 14  2011 named.conf

-rw-r----- 1 rootnamed  955 Jan 14  2011 named.rfc1912.zones

-rw-r--r-- 1 rootroot  3519 Feb 27  2006 localtime

 

-------编辑刚刚创建的 named.conf文件，按照如下方式修改：

 listen-on port 53 { 127.0.0.1; };

 allow-query { localhost; };

 match-clients { localhost; };

 match-destinations { localhost; };

 allow-query-cache { localhost; };

将上述entry中的 host信息全部修改为 any，注意保留源文件中的空格

 

 

2、配置正向解析和反向解析 zone

------配置正向解析 zone

[root@rac1 etc]# vinamed.rfc1912.zones

zone"oracle.com" IN {

 type master;

 file "rac.oracle.zone";

 allow-update { none; };

};

 

------配置反向解析 zone

[root@rac1 etc]# vinamed.rfc1912.zones

zone"8.168.192.in-addr.arpa" IN {

 type master;

 file "rac.oracle.local";

 allow-update { none; };

};

 

这里需要注意的是，反向解析从左到右读取ip地址时是以相反的方向解释的，所以需要将ip地址反向排列。

这里，192.168.8.*网段的反向解析域名为"8.168.192.in-addr.arpa"。

 

3、利用模板文件创建用于正向解析和反向解析数据库文件

[root@rac1 etc]# cd/var/named/chroot/var/named

[root@rac1 named]#ls -lt

total 44

-rw-r----- 1root  named  198 Jan 14 2011 localdomain.zone

-rw-r----- 1root  named  195 Jan 14 2011 localhost.zone

-rw-r----- 1root  named  427 Jan 14 2011 named.broadcast

-rw-r----- 1root  named 1892 Jan 14  2011 named.ca

-rw-r----- 1root  named  424 Jan 14 2011 named.ip6.local

-rw-r----- 1root  named  426 Jan 14 2011 named.local

-rw-r----- 1root  named  427 Jan 14 2011 named.zero

drwxrwx--- 2 namednamed 4096 Aug 26  2004 data

drwxrwx--- 2 namednamed 4096 Jul 27  2004 slaves

 

-----创建正向解析数据库文件

[root@rac1named]#  cp -p localhost.zonerac.oracle.zone

 

-----创建方向解析数据库文件

[root@rac1named]#  cp -p named.localrac.oracle.local

 

-----配置正向解析数据库文件

[root@rac1 named]#vim rac.oracle.zone

$TTL 86400

@ IN SOA oracle.comroot.oracle.com (

 42 ; serial (d. adams)

 3H ; refresh

 15M ; retry

 1W ; expiry

 1D ) ; minimum

 IN NS oracle.com

rac-scan IN A192.168.8.31

rac-scan IN A192.168.8.32

rac-scan IN A192.168.8.33

 

注意：无论RAC有多少节点，SCAN VIP 的个数只能有3个

 

-----配置反向解析数据库文件

[root@rac1 named]#vim rac.oracle.local

 

$TTL 86400

@ IN SOA oracle.com.root.oracle.com. (

 1997022700 ; Serial

 28800 ; Refresh

 14400 ; Retry

 3600000 ; Expire

 86400 ) ; Minimum

 IN NS oracle.com.

31 IN PTRrac-scan.oracle.com.

32 IN PTRrac-scan.oracle.com.

33 IN PTRrac-scan.oracle.com.

 

注意：

（1） 数字写IP 地址的最后一个。如192.168.6.100, 就写100

（2） rac-scan. 后面有一个点

 

4、重启 DNS Server

[root@rac1 named]#service named restart

Stopping named:[  OK ]

Starting named:[  OK ]

 

 

5、配置 DNS客户端

[root@rac1 named]#more /etc/resolv.conf

#search oracle.com

#nameserver 8.8.8.8

nameserver192.168.8.11

 

注意，如有必要刻意修改 /etc/nsswitch.conf文件配置主机解析方式

 

6、验证 DNS配置

[root@rac1 named]#nslookup 192.168.8.32

Server:         192.168.8.11

Address:        192.168.8.11#53

 

32.8.168.192.in-addr.arpa       name = rac-scan.oracle.com.

 

[root@rac1 named]#cd /var/named/chroot/var/named

[root@rac1 named]#nslookup rac-scan

Server:         192.168.8.11

Address:        192.168.8.11#53

 

Name:   rac-scan.oracle.com

Address:192.168.8.31

Name:   rac-scan.oracle.com

Address:192.168.8.32

Name:   rac-scan.oracle.com

Address:192.168.8.33

 

[root@rac1 named]#nslookup rac-scan.oracle.com

Server:         192.168.8.11

Address:        192.168.8.11#53

 

Name:   rac-scan.oracle.com

Address:192.168.8.33

Name:   rac-scan.oracle.com

Address:192.168.8.31

Name:   rac-scan.oracle.com

Address:192.168.8.32

 

 

[root@rac1 named]#nslookup 192.168.8.32

Server:         192.168.8.11

Address:        192.168.8.11#53

 

32.8.168.192.in-addr.arpa       name = rac-scan.oracle.com.

 

#eth0 - PUBLIC

192.168.8.11rac1.oracle.com rac1

192.168.8.12rac2.oracle.com rac2

#VIP

192.168.8.21rac1-vip.oracle.com rac1-vip

192.168.8.22rac2-vip.oracle.com rac2-vip

#eth1 - PRIVATE

10.10.10.11rac1-priv1

10.10.10.12rac2-priv2