Mysql进阶(4)——基于MHA的MySQL高可用架构
前言
MySQL高可用性大杀器之MHA
MHA(Master High Availability)目前在MySQL高可用方面是一个相对成熟的解决方案,它由日本DeNA公司youshimaton(现就职于 Facebook公司)开发,是一套优秀的作为MySQL高可用性环境下故障切换和主从提升的高可用软件。在MySQL故障切换过程中,MHA能做到在 0~30秒之内自动完成数据库的故障切换操作,并且在进行故障切换的过程中,MHA能在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。
该软件由两部分组成:MHA Manager(管理节点)和MHA Node(数据节点)。MHA Manager可以单独部署在一台独立的机器上管理多个master-slave集群,也可以部署在一台slave节点上。MHA Node运行在每台MySQL服务器上,MHA Manager会定时探测集群中的master节点,当master出现故障时,它可以自动将最新数据的slave提升为新的master,然后将所有其 他的slave重新指向新的master。整个故障转移过程对应用程序完全透明。
在MHA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的不丢失,但这并不总是可行的。例如,如果主服务器 硬件故障或无法通过ssh访问,MHA没法保存二进制日志,只进行故障转移而丢失了最新的数据。使用MySQL 5.5的半同步复制,可以大大降低数据丢失的风险。MHA可以与半同步复制结合起来。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主要支持一主多从的架构,要搭建MHA,要求一个复制集群中必须最少有三台数据库服务器,一主二从,即一台充当master,一台充当备用master,另外一台充当从库,因为至少需要三台服务器,出于机器成本的考虑,淘宝也在该基础上进行了改造,目前淘宝TMHA已经支持一主一从。
要求和原理:
(1)需要奇数个节点
(2)当一个master节点挂掉之后投票选出一个新的master,偶数个节点会出现票数相同的状况,但奇数个就不会
(3)所有数据节点的数据一致,每一台数据节点都有可能作为master
(4)每个节点都要安装master和slave插件;
实验环境:
主机名 | IP | 角色 |
---|---|---|
server1 | 172.25.6.1 | master |
server2 | 172.25.6.2 | slave(备master) |
server3 | 172.25.6.3 | slave |
server4 | 172.25.6.4 | MHA |
配置过程
1.(1)重新配置server1的mysql服务
[root@server1 mysql]# systemctl stop mysqld [root@server1 mysql]# vim /etc/my.cnf [root@server1 mysql]# ls 29 server-id=1 30 gtid_mode=ON 31 enforce_gtid_consistency=ON 32 log_bin=binlog 33 log_slave_updates=ON [root@server1 mysql]# pwd /var/lib/mysql [root@server1 mysql]# rm -fr * [root@server1 mysql]# ls [root@server1 mysql]# systemctl start mysqld [root@server1 mysql]# grep password /var/log/mysqld.log [root@server1 mysql]# mysql -p mysql> alter user root@localhost identified by 'ZHOUpeng123.'; mysql> show databases; mysql> GRANT REPLICATION SLAVE ON *.* TO repl@'172.25.6.%' IDENTIFIED BY 'ZHOUpeng123.'; mysql> SHOW MASTER STATUS;
(2)配置server2的mysql服务
[root@server2 ~]# systemctl stop mysqld [root@server2 ~]# cd /var/lib/mysql [root@server2 mysql]# ls [root@server2 mysql]# rm -fr * [root@server2 mysql]# ls [root@server2 mysql]# vim /etc/my.cnf server-id = 2 gtid_mode=ON enforce_gtid_consistency=ON log_slave_updates=ON log_bin=binlog [root@server2 mysql]# systemctl start mysqld [root@server2 mysql]# grep password /var/log/mysqld.log [root@server2 mysql]# mysql -p mysql> alter user root@localhost identified by 'ZHOUpeng123.'; mysql> show databases; mysql> CHANGE MASTER TO MASTER_HOST='172.25.6.1',MASTER_USER='repl', MASTER_PASSWORD='ZHOUpeng123.',MASTER_AUTO_POSITION=1; mysql> START SLAVE; mysql> SHOW SLAVE STATUS\G
(3)配置server3的mysql服务
[root@server3 ~]# systemctl stop mysqld [root@server3 ~]# cd /var/lib [root@server3 lib]# cd mysql [root@server3 mysql]# ls server-id=3 gtid_mode=ON enforce_gtid_consistency=ON log_slave_updates=ON log_bin=binlog [root@server3 mysql]# rm -fr * [root@server3 mysql]# ls [root@server3 mysql]# vim /etc/my.cnf [root@server3 mysql]# systemctl start mysqld [root@server3 mysql]# grep password /var/log/mysqld.log [root@server3 mysql]# mysql -p mysql> alter user root@localhost identified by 'ZHOUpeng123.'; mysql> show databases; mysql> CHANGE MASTER TO MASTER_HOST='172.25.6.1',MASTER_USER='repl', MASTER_PASSWORD='ZHOUpeng123.',MASTER_AUTO_POSITION=1; mysql> START SLAVE; mysql> SHOW SLAVE STATUS\G
2.测试主从复制
server1:
mysql> create database redhat; mysql> use redhat; mysql> create table usertb ( -> username varchar(10) not null, -> password varchar(15) not null); mysql> insert into usertb values ('user1','123'); mysql> select * from usertb;
server2:
mysql> select * from redhat.usertb;
server3:
mysql> select * from redhat.usertb;
备份数据库 :
[root@server1 ~]# mysqldump --all-databases --single-transaction --triggers --routines --events --host=127.0.0.1 --port=3306 --user=root --password=ZHOUpeng123. > test.sql
一、手动同步
1.server4上安装需要的软件
[root@server4 MHA-7]# yum install mha4mysql-manager-0.58-0.el7.centos.noarch.rpm mha4mysql-node-0.58-0.el7.centos.noarch.rpm perl-*
2.生成ssh密钥,管理节点是不需要输入密码,将生成的公钥和私钥传给数据节点
[root@server4 ~]# ssh-keygen [root@server4 ~]# ssh-copy-id server1 [root@server4 ~]# ssh-copy-id server2 [root@server4 ~]# ssh-copy-id server3
[root@server4 ~]# scp -r .ssh server1: [root@server4 ~]# scp -r .ssh server2: [root@server4 ~]# scp -r .ssh server3:
测试:
实现免密登陆
[root@server4 ~]# ssh server1 [root@server4 ~]# ssh server2 [root@server4 ~]# ssh server3
.
3.将节点的安装包传给数据节点
[root@server4 ~]# ls MHA-7 [root@server4 ~]# cd MHA-7/ [root@server4 MHA-7]# ls [root@server4 MHA-7]# scp -r mha4mysql-node-0.58-0.el7.centos.noarch.rpm server1:/root/ [root@server4 MHA-7]# scp -r mha4mysql-node-0.58-0.el7.centos.noarch.rpm server2:/root/ [root@server4 MHA-7]# scp -r mha4mysql-node-0.58-0.el7.centos.noarch.rpm server3:/root/
4.数据节点安装
[root@server1 ~]# yum install -y mha4mysql-node-0.58-0.el7.centos.noarch.rpm [root@server2 ~]# yum install -y mha4mysql-node-0.58-0.el7.centos.noarch.rpm [root@server3 ~]# yum install -y mha4mysql-node-0.58-0.el7.centos.noarch.rpm
5.管理节点创建一个目录,编辑配置文件
[root@server4 ~]# mkdir -p /etc/masterha [root@server4 ~]# cd /etc/masterha/ [root@server4 masterha]# ls [root@server4 masterha]# [root@server4 masterha]# vim zp.cnf [root@server4 masterha]# [root@server4 masterha]# cd [server default] manager_workdir=/etc/masterha manager_log=/var/log/masterha.log master_binlog_dir=/etc/masterha #master_ip_failover_script= /usr/local/bin/master_ip_failover #master_ip_online_change_script= /usr/local/bin/master_ip_online_change password=ZHOUpeng123. user=root ping_interval=1 remote_workdir=/tmp repl_password=ZHOUpeng123. repl_user=repl #report_script=/usr/local/send_report #secondary_check_script= /usr/local/bin/masterha_secondary_check -s server03 -s server02 #shutdown_script="" ssh_user=root [server1] hostname=172.25.6.1 port=3306 [server2] hostname=172.25.6.2 port=3306 candidate_master=1 check_repl_delay=0 [server3] hostname=172.25.6.3 port=3306 no_master=1
6.管理节点ssh检查
[root@server4 ~]# masterha_check_ssh --conf=/etc/masterha/zp.cnf
7.数据节点授权
server1: 所有权限
mysql> grant all on *.* to root@'%' identified by 'ZHOUpeng123.';
server2 和 server3: 只读
mysql> set global read_only=1;
8.管理节点环境健康检查
[root@server4 ~]# masterha_check_repl --conf=/etc/masterha/app1.cnf MySQL Replication Health is OK.
9. 手动替换master
(1)关闭当前的master节点的mysql服务
[root@server1 ~]# systemctl stop mysqld
(2)手动替换master节点
[root@server4 ~]# masterha_master_switch --master_state=dead --conf=/etc/masterha/zp.cnf --dead_master_host=172.25.6.1 --dead_master_port=3306 --new_master_host=172.25.6.2 --new_master_port=3306
(3)开启server1的master服务,将他的master改为server2
[root@server1 ~]# systemctl start mysqld[root@server1 ~]# mysql -p mysql> CHANGE MASTER TO MASTER_HOST='172.25.6.2',MASTER_USER='repl', MASTER_PASSWORD='ZHOUpeng123.',MASTER_AUTO_POSITION=1; ## 打开slave mysql> start slave;
测试:
server1:
mysql> show slave status\G
server2:
查看不出来
mysql> show slave status\G
server3:
mysql> show slave status\G
由此实现了当master节点出现故障,节点的手动切换;下面我们将要演示master节点的自动切换
二、自动切换
1.删除故障文件
[root@server4 ~]# cd /etc/masterha/ [root@server4 masterha]# ls zp.cnf zp.failover.complete [root@server4 masterha]# [root@server4 masterha]# rm -fr zp.failover.complete [root@server4 masterha]# ls
2.输入命令自动替换
masterha_master_switch --conf=/etc/masterha/zp.cnf --master_state=alive -- new_master_host=172.25.6.1 --new_master_port=3306 --orig_master_is_new_slave -- running_updates_limit=10000
测试
server1: 查看不到
mysql> mysql> show slave status\GEmpty set (0.00 sec)
server2和server3: master是server1
mysql> mysql> show slave status\G
三、自动切换
1.server4创建一个检测进程
[root@server4 masterha]# nohup masterha_manager --conf=/etc/masterha/zp.cnf &> /dev/null & [root@server4 masterha]# ps a
2.server1(当前master关闭myslq服务)
[root@server1 ~]# systemctl stop mysqld
3.server4上监控进程停止
4.server2上查看不到
mysql> show slave status\G
server3上查看到master是server2
5.server1重新开启master
[root@server1 ~]# systemctl start mysqld
配置主从复制
[root@server1 ~]# mysql -p mysql> CHANGE MASTER TO MASTER_HOST='172.25.6.2',MASTER_USER='repl', MASTER_PASSWORD='ZHOUpeng123.',MASTER_AUTO_POSITION=1; 打开slave mysql> start slave;
查看master是server2
mysql> show slave status\G
四、脚本控制(通过vip的漂移查看)
1.编辑配置文件,将以下两行的注释打开
master_ip_failover_script= /usr/local/bin/master_ip_failover master_ip_online_change_script= /usr/local/bin/master_ip_online_change
2.编写两个脚本,主要内容如下:(脚本全文在本文尾附上)
[root@server4 ~]# vim master_ip_failover
[root@server4 ~]# vim master_ip_online_change
3.将这两个脚本复制到/usr/local/bin下
[root@server4 ~]# cp master_ip_* /usr/local/bin/
4.给两个脚本加上可执行权限
[root@server4 ~]# chmod +x /usr/local/bin/master_ip_* [root@server4 ~]# [root@server4 ~]# ll /usr/local/bin/master_ip_*
5.给server2(当前master)上添加一个vip
[root@server2 ~]# ip addr add 172.25.6.100/24 dev eth0 [root@server2 ~]# ip addr
6.server4 手动切换master到server1
[root@server4 bin]# masterha_master_switch --conf=/etc/masterha/zp.cnf --master_state=alive --new_master_host=172.25.6.1 --new_master_port=3306 --orig_master_is_new_slave --running_updates_limit=10000
可以看到这个切换的过程
7.测试:
server1可以查看到vip
[root@server1 ~]# ip addr
[root@server2 ~]# ip addr ##server2上的vip自动删除
server3查看现在的master是server1
五、自动切换
1.删除故障文件
[root@server4 masterha]# ls zp.cnf zp.failover.complete [root@server4 masterha]# rm -rf zp.failover.complete [root@server4 masterha]# ls zp.cnf
2.创建监控master的进程
[root@server4 masterha]# nohup masterha_manager --conf=/etc/masterha/zp.cnf &> /dev/null & [root@server4 masterha]# ps a
3.server1关闭mysql服务
[root@server1 ~]# systemctl stop mysqld
4.监控master的进程挂掉
5.测试:
server2可以查看到vip
[root@server2 ~]# ip a
server3查看到master是server2
注意:每一次切换都会生成一个app1.failover.complete文件(简称故障文件),要将这个文件删除,否则会出错
创建一个监控master的进程,这个进程会实时监控master节点的状态,一旦master节点出现故障(宕机),server4(管理节点)就会自动执行/usr/local/bin下的两个脚本,在正常运行的节点中选择一个最新的来作为新的master节点,同时当前的进程更会挂掉,因为他监控的master已经不再当前集群
脚本详情
master_ip_failover
#!/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 ); my $vip = '172.25.6.100/24'; my $key = '1'; my $ssh_start_vip = "/sbin/ip addr add $vip dev eth0"; my $ssh_stop_vip = "/sbin/ip addr del $vip dev eth0"; GetOptions( 'command=s' => \$command, 'ssh_user=s' => \$ssh_user, 'orig_master_host=s' => \$orig_master_host, 'orig_master_ip=s' => \$orig_master_ip, 'orig_master_port=i' => \$orig_master_port, 'new_master_host=s' => \$new_master_host, 'new_master_ip=s' => \$new_master_ip, 'new_master_port=i' => \$new_master_port, ); exit &main(); sub main { print "\n\nIN SCRIPT TEST====$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 \" $ssh_start_vip \"`; } sub stop_vip() { return 0 unless ($ssh_user); `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"; }
master_ip_online_change
#!/usr/bin/env perl use strict; use warnings FATAL =>'all'; use Getopt::Long; my $vip = '172.25.6.100/24'; # Virtual IP my $key = "1"; my $ssh_start_vip = "/sbin/ip addr add $vip dev eth0"; my $ssh_stop_vip = "/sbin/ip addr del $vip dev eth0"; my $exit_code = 0; my ( $command, $orig_master_is_new_slave, $orig_master_host, $orig_master_ip, $orig_master_port, $orig_master_user, $orig_master_password, $orig_master_ssh_user, $new_master_host, $new_master_ip, $new_master_port, $new_master_user, $new_master_password, $new_master_ssh_user, ); GetOptions( 'command=s' => \$command, 'orig_master_is_new_slave' => \$orig_master_is_new_slave, 'orig_master_host=s' => \$orig_master_host, 'orig_master_ip=s' => \$orig_master_ip, 'orig_master_port=i' => \$orig_master_port, 'orig_master_user=s' => \$orig_master_user, 'orig_master_password=s' => \$orig_master_password, 'orig_master_ssh_user=s' => \$orig_master_ssh_user, 'new_master_host=s' => \$new_master_host, 'new_master_ip=s' => \$new_master_ip, 'new_master_port=i' => \$new_master_port, 'new_master_user=s' => \$new_master_user, 'new_master_password=s' => \$new_master_password, 'new_master_ssh_user=s' => \$new_master_ssh_user, ); exit &main(); sub main { #print "\n\nIN SCRIPT TEST====$ssh_stop_vip==$ssh_start_vip===\n\n"; if ( $command eq "stop" || $command eq "stopssh" ) { # $orig_master_host, $orig_master_ip, $orig_master_port are passed. # If you manage master ip address at global catalog database, # invalidate orig_master_ip here. my $exit_code = 1; eval { print "\n\n\n***************************************************************\n"; print "Disabling the VIP - $vip on old master: $orig_master_host\n"; print "***************************************************************\n\n\n\n"; &stop_vip(); $exit_code = 0; }; if ($@) { warn "Got Error: $@\n"; exit $exit_code; } exit $exit_code; } elsif ( $command eq "start" ) { # all arguments are passed. # If you manage master ip address at global catalog database, # activate new_master_ip here. # You can also grant write access (create user, set read_only=0, etc) here. my $exit_code = 10; eval { print "\n\n\n***************************************************************\n"; print "Enabling the VIP - $vip on new master: $new_master_host \n"; print "***************************************************************\n\n\n\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"; `ssh $orig_master_ssh_user\@$orig_master_host \" $ssh_start_vip \"`; exit 0; } else { &usage(); exit 1; } } # A simple system call that enable the VIP on the new master sub start_vip() { `ssh $new_master_ssh_user\@$new_master_host \" $ssh_start_vip \"`; } # A simple system call that disable the VIP on the old_master sub stop_vip() { `ssh $orig_master_ssh_user\@$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"; }
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