一步一步在Linux上安装Oracle 11gR2 RAC (2)

2.2 配置 /etc/hosts文件
参照Figure 2.1网络配置信息表，修改节点1的/etc/hosts配置文件。
[root@node1 ~]# cp /etc/hosts /etc/hosts.bak
[root@node1 ~]# cat /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost
::1 localhost6.localdomain6 localhost6
# node1
172.16.0.191 node1.localdomain node1
172.16.0.193 node1-vip.localdomain node1-vip
192.168.94.11 node1-priv.localdomain node1-priv
# node2
172.16.0.192 node2.localdomain node2
172.16.0.194 node2-vip.localdomain node2-vip
192.168.94.12 node2-priv.localdomain node2-priv
# scan-ip
172.16.0.203 scan-cluster.localdomain scan-cluster
[root@node1 ~]#

2.3 配置DNS服务器，确认SCAN IP可以被解析
从Oracle 11gR2开始，引入SCAN(Single Client Access Name) IP的概念，相当于在客户端和数据库之间增加一层虚拟的网络服务层，即是SCAN IP和SCAP IP Listener。在客户端的tnsnames.ora配置文件中，只需要配置SCAN IP的配置信息即可，客户端通过SCAN IP、SCAN IP Listener来访问数据库。同之前各版本的RAC相比，使用SCAN IP的好处就是，当后台RAC数据库添加、删除节点时，客户端配置信息无需修改。可以通过配置DNS服务器或GNS来配置SCAN，我们这里以DNS为例来进行配置。

2.3.1 配置DNS服务器

这里，选择IP地址为172.16.0.176的服务器来配置DNS服务器。

①安装DNS软件包：

[root@rdd dns_rpm]# ifconfig eth0

eth0 Link encap:Ethernet HWaddr 00:0C:29:99:DA:22

inet addr:172.16.0.176 Bcast:172.16.15.255 Mask:255.255.240.0

inet6 addr: fe80::20c:29ff:fe99:da22/64 Scope:Link

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

RX packets:10237921 errors:0 dropped:0 overruns:0 frame:0

TX packets:1394986 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:3375785216 (3.1 GiB) TX bytes:596171214 (568.5 MiB)

[root@rdd dns_rpm]# pwd

/root/dns_rpm

[root@rdd dns_rpm]# ll

total 1112

-rw-r--r-- 1 root root 1015531 Apr 23 14:53 bind-9.3.6-4.P1.el5_4.2.x86_64.rpm

-rw-r--r-- 1 root root 45360 Apr 23 14:53 bind-chroot-9.3.6-4.P1.el5_4.2.x86_64.rpm

-rw-r--r-- 1 root root 62251 Apr 23 14:53 caching-nameserver-9.3.6-4.P1.el5_4.2.x86_64.rpm

[root@rdd dns_rpm]# rpm -ivh bind-9.3.6-4.P1.el5_4.2.x86_64.rpm

warning: bind-9.3.6-4.P1.el5_4.2.x86_64.rpm: Header V3 DSA signature: NOKEY, key ID 1e5e0159

Preparing... ########################################### [100%]

1:bind ########################################### [100%]

[root@rdd dns_rpm]# rpm -ivh bind-chroot-9.3.6-4.P1.el5_4.2.x86_64.rpm

warning: bind-chroot-9.3.6-4.P1.el5_4.2.x86_64.rpm: Header V3 DSA signature: NOKEY, key ID 1e5e0159

Preparing... ########################################### [100%]

1:bind-chroot ########################################### [100%]

[root@rdd dns_rpm]# rpm -ivh caching-nameserver-9.3.6-4.P1.el5_4.2.x86_64.rpm

warning: caching-nameserver-9.3.6-4.P1.el5_4.2.x86_64.rpm: Header V3 DSA signature: NOKEY, key ID 1e5e0159

Preparing... ########################################### [100%]

1:caching-nameserver ########################################### [100%]

[root@rdd dns_rpm]#

② 配置/var/named/chroot/etc/named.conf文件

先拷贝生成该文件：

[root@rdd dns_rpm]# cd /var/named/chroot/etc/

[root@rdd etc]# ll

total 16

-rw-r--r-- 1 root root 405 Apr 18 07:50 localtime

-rw-r----- 1 root named 1230 Jan 21 2010 named.caching-nameserver.conf

-rw-r----- 1 root named 955 Jan 21 2010 named.rfc1912.zones

-rw-r----- 1 root named 113 Apr 23 14:55 rndc.key

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

[root@rdd etc]#

修改后的该文件内容如下：

[root@rdd etc]# pwd

/var/named/chroot/etc

[root@rdd etc]# cat named.conf

//

// named.caching-nameserver.conf

//

// Provided by Red Hat caching-nameserver package to configure the

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

// (as a localhost DNS resolver only).

//

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

//

// DO NOT EDIT THIS FILE - use system-config-bind or an editor

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

// caching-nameserver package upgrade.

//

options {

listen-on port 53 { any; };

listen-on-v6 port 53 { ::1; };

directory "/var/named";

dump-file "/var/named/data/cache_dump.db";

statistics-file "/var/named/data/named_stats.txt";

memstatistics-file "/var/named/data/named_mem_stats.txt";

// Those options should be used carefully because they disable port

// randomization

// query-source port 53;

// query-source-v6 port 53;

allow-query { any; };

allow-query-cache { any; };

};

logging {

channel default_debug {

file "data/named.run";

severity dynamic;

};

};

view localhost_resolver {

match-clients { any; };

match-destinations { any; };

recursion yes;

include "/etc/named.rfc1912.zones";

};

[root@rdd etc]#

说明：为简单起见，将该文件中的127.0.0.1、localhost全部修改成any，且修改时，需要注意左右两边留空格。修改部分在上述配置文件中以红色加粗标示。

通过拷贝来生成/var/named/chroot/etc/named.conf文件时，注意加上-p选项，来保证文件的权限问题，否则会导致DNS服务启不来！

③ 配置Zone文件，修改/var/named/chroot/etc/named.rfc1912.zones文件

配置Zone的目的是为了解析SCAN IP，在该文件末尾添加以下反向Zone：

zone "0.16.172.in-addr.arpa." IN {

type master;

file "0.16.172.in-addr.arpa";

allow-update { none; };

};

配置反向Zone之后的该文件内容如下：

[root@rdd etc]# pwd

/var/named/chroot/etc

[root@rdd etc]# ll

total 20

-rw-r--r-- 1 root root 405 Apr 18 07:50 localtime

-rw-r----- 1 root named 1230 Jan 21 2010 named.caching-nameserver.conf

-rw-r----- 1 root root 1200 Apr 23 15:03 named.conf

-rw-r----- 1 root named 1085 Apr 23 15:19 named.rfc1912.zones

-rw-r----- 1 root named 113 Apr 23 14:55 rndc.key

[root@rdd etc]# cat named.rfc1912.zones

// named.rfc1912.zones:

//

// Provided by Red Hat caching-nameserver package

//

// ISC BIND named zone configuration for zones recommended by

// RFC 1912 section 4.1 : localhost TLDs and address zones

//

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

//

zone "." IN {

type hint;

file "named.ca";

};

zone "localdomain" IN {

type master;

file "localdomain.zone";

allow-update { none; };

};

zone "localhost" IN {

type master;

file "localhost.zone";

allow-update { none; };

};

zone "0.0.127.in-addr.arpa" IN {

type master;

file "named.local";

allow-update { none; };

};

zone "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa" IN {

type master;

file "named.ip6.local";

allow-update { none; };

};

zone "255.in-addr.arpa" IN {

type master;

file "named.broadcast";

allow-update { none; };

};

zone "0.in-addr.arpa" IN {

type master;

file "named.zero";

allow-update { none; };

};

zone "0.16.172.in-addr.arpa." IN {

type master;

file "0.16.172.in-addr.arpa";

allow-update { none; };

};

[root@rdd etc]#

说明：正常情况下还应该配置正向Zone文件。这里，我们的RAC双节点node1、node2的域名domain都设置为localdomain，而默认情况下，该配置文件(/var/named/chroot/etc/named.rfc1912.zones)的第15行到第20行中已经自带下述正向Zone文件配置信息，所以无需再添加。

zone "localdomain" IN {

type master;

file "localdomain.zone";

allow-update { none; };

};

④ 配置正、反向解析数据库文件。在/var/named/chroot/var/named路径下进行配置

首先，生成正、反向解析数据库文件。利用/var/named/chroot/var/named/localhost.zone复制生成正向解析的数据库文件，利用/var/named/chroot/var/named/localhost.zone复制生成名为0.16.172.in-addr.arpa的反向解析的数据库文件。

[root@rdd etc]# pwd

/var/named/chroot/etc

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

[root@rdd named]# ll

total 36

drwxrwx--- 2 named named 4096 Aug 26 2004 data

-rw-r----- 1 root named 198 Jan 21 2010 localdomain.zone

-rw-r----- 1 root named 195 Jan 21 2010 localhost.zone

-rw-r----- 1 root named 427 Jan 21 2010 named.broadcast

-rw-r----- 1 root named 1892 Jan 21 2010 named.ca

-rw-r----- 1 root named 424 Jan 21 2010 named.ip6.local

-rw-r----- 1 root named 426 Jan 21 2010 named.local

-rw-r----- 1 root named 427 Jan 21 2010 named.zero

drwxrwx--- 2 named named 4096 Jul 27 2004 slaves

[root@rdd named]# cp -p named.local 0.16.172.in-addr.arpa

[root@rdd named]# ll

total 40

-rw-r----- 1 root named 426 Apr 23 16:10 0.16.172.in-addr.arpa

drwxrwx--- 2 named named 4096 Aug 26 2004 data

-rw-r----- 1 root named 198 Jan 21 2010 localdomain.zone

-rw-r----- 1 root named 195 Jan 21 2010 localhost.zone

-rw-r----- 1 root named 427 Jan 21 2010 named.broadcast

-rw-r----- 1 root named 1892 Jan 21 2010 named.ca

-rw-r----- 1 root named 424 Jan 21 2010 named.ip6.local

-rw-r----- 1 root named 426 Jan 21 2010 named.local

-rw-r----- 1 root named 427 Jan 21 2010 named.zero

drwxrwx--- 2 named named 4096 Jul 27 2004 slaves

[root@rdd named]#

说明：在上述步骤③中我们没有配置正向Zone文件，故只需生成反向解析数据库文件，正向解析数据库文件利用默认的localdomain.zone文件。

生成的正、反向解析数据库文件名一定要同上述步骤③中定义的正、反向Zone文件一致，否则DNS出错！

然后，定义正、反向解析数据库文件。

在正向解析数据库文件localdomain.zone末尾添加下述内容：

scan-cluster IN A 172.16.0.203

添加后内容如下：

[root@rdd named]# pwd

/var/named/chroot/var/named

[root@rdd named]# cat localdomain.zone

$TTL 86400

@ IN SOA localhost root (

42 ; serial (d. adams)

3H ; refresh

15M ; retry

1W ; expiry

1D ) ; minimum

IN NS localhost

localhost IN A 127.0.0.1

scan-cluster IN A 172.16.0.203

[root@rdd named]#

在反向解析数据库文件0.16.172.in-addr.arpa末尾添加下述内容：

203 IN PTR scan-cluster.localdomain.

添加后内容如下：

[root@rdd named]# pwd

/var/named/chroot/var/named

[root@rdd named]# cat 0.16.172.in-addr.arpa

$TTL 86400

@ IN SOA localhost. root.localhost. (

1997022700 ; Serial

28800 ; Refresh

14400 ; Retry

3600000 ; Expire

86400 ) ; Minimum

IN NS localhost.

1 IN PTR localhost.

203 IN PTR scan-cluster.localdomain.

[root@rdd named]#

2.3.2 测试DNS服务器解析SCAN IP正常

首先，在DNS服务器172.16.0.176上启动DNS服务：

[root@rdd named]# /etc/init.d/named status

rndc: connect failed: 127.0.0.1#953: connection refused

named is stopped

[root@rdd named]# /etc/init.d/named start

Starting named: [ OK ]

[root@rdd named]# /etc/init.d/named status

number of zones: 7

debug level: 0

xfers running: 0

xfers deferred: 0

soa queries in progress: 0

query logging is OFF

recursive clients: 0/1000

tcp clients: 0/100

server is up and running

named (pid 23307) is running...

[root@rdd named]# chkconfig named on

[root@rdd named]#

然后，分别在RAC节点node1、node2的/etc/resolv.conf配置文件中添加下述配置信息：

search localdomain

nameserver 172.16.0.176

添加之后：

[root@node1 ~]# cat /etc/resolv.conf

search localdomain

nameserver 172.16.0.176

[root@node1 ~]#

最后，测试SCAN IP解析是否成功？

node1测试：

[root@node1 ~]# nslookup 172.16.0.203

Server: 172.16.0.176

Address: 172.16.0.176#53

203.0.16.172.in-addr.arpa name = scan-cluster.localdomain.

[root@node1 ~]# nslookup scan-cluster.localdomain

Server: 172.16.0.176

Address: 172.16.0.176#53

Name: scan-cluster.localdomain

Address: 172.16.0.203

[root@node1 ~]# nslookup scan-cluster

Server: 172.16.0.176

Address: 172.16.0.176#53

Name: scan-cluster.localdomain

Address: 172.16.0.203

[root@node1 ~]#

node2测试：

[root@node2 ~]# nslookup 172.16.0.203

Server: 172.16.0.176

Address: 172.16.0.176#53

203.0.16.172.in-addr.arpa name = scan-cluster.localdomain.

[root@node2 ~]# nslookup scan-cluster.localdomain

Server: 172.16.0.176

Address: 172.16.0.176#53

Name: scan-cluster.localdomain

Address: 172.16.0.203

[root@node2 ~]# nslookup scan-cluster

Server: 172.16.0.176

Address: 172.16.0.176#53

Name: scan-cluster.localdomain

Address: 172.16.0.203

[root@node2 ~]#

至此，准备工作中的配置SCAN IP通过配置DNS服务器来解析已经成功！