本文爲南非螞蟻的書籍《循序漸進linux-第二版》-8.3.6的讀筆記
在DB1和DB2上安裝Keepalived軟件
先安裝編譯工具
# yum install gcc* gcc-c++ autoconf automake
上傳keepalived-1.2.19.tar.gz至/server/tools目錄下
# cd /server/tools
# tar zxvf keepalived-1.2.19.tar.gz
# cd keepalived-1.2.19
# ./configure --sysconf=/etc --with-kernel-dir=/usr/src/kernels/2.6.32-504.el6.x86_64/
# make
# make install
# ln -s /usr/local/sbin/keepalived /sbin/
# chkconfig --add keepalived
# chkconfig --level 35 keepalived on
# cd ../
安裝完成後，進入DB1的配置過程
DB1服務器上/etc/keepalived/keepalived.conf的配置內容，其中綠色字體爲新增部分
! Configuration File for keepalived
global_defs {
notification_email {
}
notification_email_from [email protected]
smtp_server 192.168.200.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_scripts check_mysqld {
scripts "/etc/keepalived/mysqlcheck/check_slave.pl 127.0.0.1" #檢測mysql複製狀態的腳本
interval 2
weight 21
}
vrrp_instance HA_1 {
state BACKUP #在DB1和DB2上均配置爲BACKUP
interface eth0
virtual_router_id 80
priority 90
advert_int 2
nopereempt #不搶佔模式，只在優先級高的機器上設置即可，優先級低的機器上不設置
authentication {
auth_type PASS
auth_pass qweasdzxc
}
track_script {
check_mysqld
}
virtual_ipaddress {
10.24.24.110/24 dev eth0 #mysql的對外服務IP，即VIP
}
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.200.16
192.168.200.17
192.168.200.18
}
}
-----------------------------------------
# mkdir /etc/keepalived/mysqlcheck/
其中，/etc/keepalived/mysqlcheck/check_slave.pl文件的內容如下：
# vim /etc/keepalived/mysqlcheck/check_slave.pl
#!/usr/bin/perl -w
use DBI;
use DBD::mysql;
# CONFIG VARIABLES
$SBM = 120;
$db = "ywadmin";
$host = $ARGV[0];
$port = 3306;
$user = "root";
$pw = "jzh0024";
# SQL query
$query = "show slave status";
$dbh = DBI->connect("DBI:mysql:$db:$host:$port", $user, $pw, { RaiseError => 0,PrintError => 0 });
if (!defined($dbh)) {
exit 1;
}
$sqlQuery = $dbh->prepare($query);
$sqlQuery->execute;
$Slave_IO_Running = "";
$Slave_SQL_Running = "";
$Seconds_Behind_Master = "";
while (my $ref = $sqlQuery->fetchrow_hashref()) {
$Slave_IO_Running = $ref->{'Slave_IO_Running'};
$Slave_SQL_Running = $ref->{'Slave_SQL_Running'};
$Seconds_Behind_Master = $ref->{'Seconds_Behind_Master'};
}
$sqlQuery->finish;
$dbh->disconnect();
if ( $Slave_IO_Running eq "No" || $Slave_SQL_Running eq "No" ) {
exit 1;
} else {
if ( $Seconds_Behind_Master > $SBM ) {
exit 1;
} else {
exit 0;
}
}
只需要修改紅色的數據庫名\數據庫端口\用戶名和密碼即可
添加可執行權限
# chmod +x /etc/keepalived/mysqlcheck/check_slave.pl
將keepalived.conf和check_slave.pl文件複製到DB2服務器對應的位置，將DB2上的keepalived.conf中的priority值修改爲90，同時去掉nopreempt選項
DB2上
[root@DB2 keepalived]# mkdir /etc/keepalived/mysqlcheck/
[root@DB2 keepalived]# cd /etc/keepalived/mysqlcheck/
上傳check_slave.pl腳本
[root@DB2 mysqlcheck]# rz
[root@DB2 mysqlcheck]# ll
total 4
-rw-r--r-- 1 root root 919 Sep 12 14:57 check_slave.pl
[root@DB2 mysqlcheck]# chmod +x check_slave.pl
完成所有配置後，分別啓動DB1和DB2上啓動keepalived服務，正常情況下VIP地址應該運行在DB1服務器上
[root@DB1 tools]# /etc/init.d/keepalived start
Starting keepalived: [ OK ]
[root@DB2 keepalived]# /etc/init.d/keepalived start
Starting keepalived: [ OK ]
======================================================
8.3.7 測試mysql主從同步功能
首先在DB1,DB2上添加遠程訪問授權;
DB1上授權
mysql> grant all on *.* to 'root'@'10.24.24.%' identified by 'jzh0024';
Query OK, 0 rows affected (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
mysql> select user,host from mysql.user;
DB2上授權
mysql> grant all on *.* to 'root'@'10.24.24.%' identified by 'jzh0024';
Query OK, 0 rows affected (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
mysql> select user,host from mysql.user;
1.在遠程客戶端通過VIP登錄測試
[root@mysql01 ~]# mysql -uroot -p -h 10.24.24.110
Enter password:
mysql> show variables like "%hostname%";
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| hostname | DB1 |
+---------------+-------+
1 row in set (0.00 sec)
mysql> show variables like "%server_id%";
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 1 |
+---------------+-------+
1 row in set (0.00 sec)
從SQL輸出結果看,可以通過VIP登錄,並且登錄到了DB1服務器
2.數據複製功能測試
[root@mysql01 ~]# mysql -uroot -p -h 10.24.24.110
Enter password:
mysql> create database repldb;
Query OK, 1 row affected (0.00 sec)
mysql> use repldb;
Database changed
mysql> create table repl_table(id int,email varchar(86),password varchar(40) not null);
Query OK, 0 rows affected (0.00 sec)
mysql> show tables;
+------------------+
| Tables_in_repldb |
+------------------+
| repl_table |
+------------------+
1 row in set (0.00 sec)
mysql> insert into repl_table (id,email,password) values(1,"[email protected]","qwessd");
Query OK, 1 row affected (0.00 sec)
mysql> select * from repl_table;
+------+----------------+----------+
| id | email | password |
+------+----------------+----------+
| 1 | [email protected] | qwessd |
+------+----------------+----------+
1 row in set (0.00 sec)
在DB2數據庫中查詢數據是否已經同步
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| db01 |
| db02 |
| mysql |
| repldb |
| ywadmin |
+--------------------+
6 rows in set (0.00 sec)
mysql> use repldb;
Database changed
mysql> show tables;
+------------------+
| Tables_in_repldb |
+------------------+
| repl_table |
+------------------+
1 row in set (0.00 sec)
mysql> select * from repl_table;
+------+----------------+----------+
| id | email | password |
+------+----------------+----------+
| 1 | [email protected] | qwessd |
+------+----------------+----------+
1 row in set (0.00 sec)
證明在其他mysql客戶端登錄寫入VIP的數據已經同步到DB2數據庫中。
======================================================
8.3.8 測試keepalived實現mysql故障切換
爲了測試keepalived實現的故障切換功能，需要模擬一些故障。
比如，可以斷開DB1主機的網絡、關閉DB1主機、關閉DB1上mysql服務等各種操作實現；
這裏停止DB1服務器的網絡連接，模擬DB1的mysql故障；
由於在DB1、DB2服務器上都添加了監控MYSQL運行狀態的腳本 check_slave.pl，因此當關閉DB1的MYSQL日誌接收功能後，keepalived會立刻檢測到，接着執行切換操作
測試過程如下：
1.停止DB1服務器的網絡連接
在遠程mysql客戶端以VIP地址登錄到mysql系統中，不要退出這個連接；
中斷DB1服務器的網絡連接;
[root@DB1 ~]# /etc/init.d/network stop
2.在mysql遠程客戶端測試
繼續在剛纔打開的遠程mysql連接中執行命令
mysql> show variables like "%hostname%";
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| hostname | DB2 |
+---------------+-------+
1 row in set (0.00 sec)
mysql> show variables like "%server_id%";
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 2 |
+---------------+-------+
1 row in set (0.00 sec)
接着重新開啓DB1的網絡連接，發現keepalived將不再執行切換操作了，因爲上面將keepalived配置爲搶佔模式了。
此時，mysql服務將一直在DB2服務器上運行，每次切換的代價很大，因而關閉了keepalived的主動搶佔模式。