前言
高可用MySQL集群是指部署了多个MySQL实例的集群,可以在节点出现故障的情况下,自动切换到另一个可用节点,保证系统的高可用性和可靠性。
一、概述
(一)、概念
MHA(MasterHigh Availability)是一套优秀的MySQL高可用环境下故障切换和主从复制的软件。
MHA 的出现就是解决MySQL 单点的问题。
MySQL故障切换过程中,MHA能做到0-30秒内自动完成故障切换操作。
MHA能在故障切换的过程中最大程度上保证数据的一致性,以达到真正意义上的高可用。
(二)、组成
MHA manager 管理节点
MHA node 数据节点 每个节点上都需要安装
(三)、特点
自动故障切换过程中,MHA试图从宕机的主服务器上保存二进制日志,最大程度的保证数据不丢失。
使用半同步复制,可以大大降低数据丢失的风险,如果只有一个slave已经收到了最新的二进制日志,MHA可以将最新的二进制日志应用于其他所有的slave服务器上,因此可以保证所有节点的数据一致性。
目前MHA支持一主多从架构,最少三台服务,即一主两从。
(四)、工作原理
- 从宕机崩溃的master 保存二进制日志事件(binlog events)
- 识别含有最新的更新slave日志
- 应用差异的中继日志(relay log)到其他的slave
- 应用从master保存的二进制日志事件
- 提升一个slave为新的master
- 使其他的slave连接新的master进行复制
二、案例
192.168.238.134 manager(MHA) 即mgt
192.168.238.135 master master
192.168.238.136 slave slave1
192.168.238.137 slave slave2
(一)、构建MHA
1.所有节点ssh免密登录
192.168.238.134
ssh-keygen
for i in 135 136 137;do ssh-copy-id root@192.168.238.$i;done
yes确认指纹,和输入对应主机的密码
192.168.238.135
ssh-keygen
for i in 134 136 137;do ssh-copy-id root@192.168.238.$i;done
yes确认指纹,和输入对应主机的密码
192.168.238.136
ssh-keygen
for i in 134 135 137;do ssh-copy-id root@192.168.238.$i;done
yes确认指纹,和输入对应主机的密码
192.168.238.135
ssh-keygen
for i in 134 135 136;do ssh-copy-id root@192.168.238.$i;done
yes确认指纹,和输入对应主机的密码
进行验证看是否免密成功逐一登录登出,确保后续脚本正常运行
以192.168.238.134为例
2、MySQL主从复制
yum install -y mariadb mariadb-server安装至master、slave1、slave2
192.168.238.135-master
vim /etc/my.cnf
server-id=10
log-bin=master-bin
log-slave-updates=true
systemctl start mariadb
除了在下图MySQL中登录授权也可以在外部授权
mysql -e "grant replication slave on *.* to 'myslave'@'192.168.238.% identified by '123.com';"
mysql -e "grant all privileges on *.* to 'mha'@'192.168.238.% identified by '123.com';"
mysql -e "grant all privileges on *.* to 'mha'@'192.168.238.134 identified by '123.com';"
mysql -e "grant all privileges on *.* to 'mha'@'192.168.238.136 identified by '123.com';"
mysql -e "grant all privileges on *.* to 'mha'@'192.168.238.137 identified by '123.com';"
查看master状态
192.168.238.136
vim /etc/my.cnf
server-id=11
log-bin=master-bin
relay-log=relay-log-bin
relay-log-index=relay-log-bin.index
systemctl start mariadb
mysql -e "grant replication slave on *.* to 'myslave'@'192.168.238.% identified by '123.com';"
mysql -e "grant all privileges on *.* to 'mha'@'192.168.238.% identified by '123.com';"
mysql -e "grant all privileges on *.* to 'mha'@'192.168.238.134 identified by '123.com';"
mysql -e "grant all privileges on *.* to 'mha'@'192.168.238.136 identified by '123.com';"
mysql -e "grant all privileges on *.* to 'mha'@'192.168.238.137 identified by '123.com';"
mysql -e "stop slave;"
mysql -e "change master to master_host ='192.168.238.135', master_user='myslave',master _password='123.com',master_log_file='master-bin.000003',master_log_pos=1163;"
mysql -e "start slave;"
查看slave状态
192.168.238.137
vim /etc/my.cnf
server-id=12
log-bin=master-bin
relay-log=relay-log-bin
relay-log-index=relay-log-bin.index
systemctl start mariadb
mysql -e "grant replication slave on *.* to 'myslave'@'192.168.238.% identified by '123.com';"
mysql -e "grant all privileges on *.* to 'mha'@'192.168.238.% identified by '123.com';"
mysql -e "grant all privileges on *.* to 'mha'@'192.168.238.134 identified by '123.com';"
mysql -e "grant all privileges on *.* to 'mha'@'192.168.238.136 identified by '123.com';"
mysql -e "grant all privileges on *.* to 'mha'@'192.168.238.137 identified by '123.com';"
mysql -e "stop slave;"
mysql -e "change master to master_host ='192.168.238.135', master_user='myslave',master _password='123.com',master_log_file='master-bin.000003',master_log_pos=1163;"
mysql -e "start slave;"
查看slave状态
验证主从关系
master create database class
slave1
slave2
(二)、MHA安装
基于主从复制模式之上
1.所有节点安装perl环境
yum install epel-release -y(一直更新到版本epel-release.noarch 0:7-14)
yum -y install perl-DBD-MySQL perl-ExtUtils-MakeMaker perl-Config-Tiny perl-Log-Dispatch perl-Parallel-ForkManager perl-Time-HiRes perl-CPAN
2.所有节点安装node
tar xf mha4mysql-node-0.57.tar.gz
cd /root/mha4mysql-noder-0.57
perl Makefile.PL && make && make install
验证
cd /usr/local/bin
看到脚本就OK
3.manager
tar xf mha4mysql-manager-0.57.tar.gz
cd /root/mha4mysql-manager-0.57
perl Makefile.PL && make && make install
cp sample/scripts/master_ip_failover /usr/local/bin/
cp sample/scripts/master_ip_online_change /usr/local/bin/
4.脚本说明
master_ip_failover 自动切换时 VIP 管理的脚本
master_ip_online_change 在线切换时 vip 的管理
power_manager 故障发生后关闭主机的脚本
send_report 因故障切换后发送报警的脚本
5.配置文件建立
mkdir /etc/masterha -p
vim /etc/masterha/app1.cnf
mkdir /var/log/masterha/app1 -p
6.测试MHA
vim /usr/local/bin/master_ip_failover
chown +x /usr/local/bin/master_ip_failover
插入脚本
#!/usr/bin/env perl
use strict;
use warnings FATAL => 'all';
use Getopt::Long;
my (
$command, $ssh_user, $orig_master_host, $orig_master_ip,
$orig_master_port, $new_master_host, $new_master_ip, $new_master_port
);
#############################添加内容部分#########################################
my $vip = '192.168.238.200'; #指定vip的地址
my $brdc = '192.168.238.255'; #指定vip的广播地址
my $ifdev = 'ens33'; #指定vip绑定的网卡
my $key = '1'; #指定vip绑定的虚拟网卡序列号
my $ssh_start_vip = "/sbin/ifconfig ens33:$key $vip"; #代表此变量值为ifconfig ens33:1 192.168.238.100
my $ssh_stop_vip = "/sbin/ifconfig ens33:$key down"; #代表此变量值为ifconfig ens33:1 192.168.238.200 down
my $exit_code = 0; #指定退出状态码为0
#my $ssh_start_vip = "/usr/sbin/ip addr add $vip/24 brd $brdc dev $ifdev label $ifdev:$key;/usr/sbin/arping -q -A -c 1 -I $ifdev $vip;iptables -F;";
#my $ssh_stop_vip = "/usr/sbin/ip addr del $vip/24 dev $ifdev label $ifdev:$key";
##################################################################################
GetOptions(
'command=s' => \$command,
'ssh_user=s' => \$ssh_user,
'orig_master_host=s' => \$orig_master_host,
'orig_master_ip=s' => \$orig_master_ip,
'orig_master_port=i' => \$orig_master_port,
'new_master_host=s' => \$new_master_host,
'new_master_ip=s' => \$new_master_ip,
'new_master_port=i' => \$new_master_port,
);
exit &main();
sub main {
print "\n\nIN SCRIPT TEST====$ssh_stop_vip==$ssh_start_vip===\n\n";
if ( $command eq "stop" || $command eq "stopssh" ) {
my $exit_code = 1;
eval {
print "Disabling the VIP on old master: $orig_master_host \n";
&stop_vip();
$exit_code = 0;
};
if ($@) {
warn "Got Error: $@\n";
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "start" ) {
my $exit_code = 10;
eval {
print "Enabling the VIP - $vip on the new master - $new_master_host \n";
&start_vip();
$exit_code = 0;
};
if ($@) {
warn $@;
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "status" ) {
print "Checking the Status of the script.. OK \n";
exit 0;
}
else {
&usage();
exit 1;
}
}
sub start_vip() {
`ssh $ssh_user\@$new_master_host \" $ssh_start_vip \"`;
}
## A simple system call that disable the VIP on the old_master
sub stop_vip() {
`ssh $ssh_user\@$orig_master_host \" $ssh_stop_vip \"`;
}
sub usage {
print
"Usage: master_ip_failover --command=start|stop|stopssh|status --orig_master_host=host --orig_master_ip=ip --orig_master_port=port --new_master_host=host --new_master_ip=ip --new_master_port=port\n";
}
masterha_check_ssh --conf=/etc/masterha/app1.cnf
masterha_check_repl --conf=/etc/masterha/app1.cnf
7.启动命令
nohup masterha_manager --conf=/etc/masterha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /var/log/masterha/app1/manager.log 2>&1 &
启动时masterIP异常
需要工程手动配置VIP
(三)、测试
停用master的mariadb服务
去slave1中查看IP
总结
今天的内容要在免密和主从复制的基础之上才能运行,搭建基础就考验小伙伴们的基本功底了,在学新知识的同时又复习了学过的知识。