MHA介绍
MHA是一位日本MySQL大牛用Perl写的一套MySQL故障切换方案，来保证数据库系统的高可用.在宕机的时间内（通常10—30秒内），完成故障切换，部署MHA，可避免主从一致性问题，节约购买新服务器的费用，不影响服务器性能，易安装，不改变现有部署。
还支持在线切换，从当前运行master切换到一个新的master上面，只需要很短的时间（0.5-2秒内），此时仅仅阻塞写操作，并不影响读操作，便于主机硬件维护。
在有高可用，数据一致性要求的系统上，MHA 提供了有用的功能，几乎无间断的满足维护需要。
优点：
1.master自动监控和故障转移
在当前已存在的主从复制环境中，MHA可以监控master主机故障，并且故障自动转移。
即使有一些slave没有接受新的relay log events，MHA也会从最新的slave自动识别差异的relay log events，并apply差异的event到其他slaves。因此所有的slave都是一致的。MHA秒级别故障转移（9-12秒监测到主机故障，任选7秒钟关闭电源主机避免脑裂，接下来apply差异relay logs，注册到新的master，通常需要时间10-30秒即total downtime）。另外，在配置文件里可以配置一个slave优先成为master。因为MHA修复了slave之间的一致性，dba就不用去处理一致性问题。
当迁移新的master之后，并行恢复其他slave。即使有成千上万的slave,也不会影响恢复master时间，slave也很快完成。
DeNA公司在150+主从环境中用MHA。当其中一个master崩溃，MHA4秒完成故障转移，这是主动/被动集群解决方案无法完成的。
2.互动(手动)master故障转移
MHA可以用来只做故障转移，而不监测master，MHA只作为故障转移的交互。
3.非交互式故障转移
非交互式的故障转移也提供（不监控master，自动故障转移）。这个特性很有用，特别是你已经安装了其他软件监控master。比如，用Pacemaker(Heartbeat)监测master故障和vip接管，用MHA故障转移和slave提升。
4.在线切换master到不同主机
在很多情况下，有必要将master转移到其他主机上（如替换raid控制器，提升master机器硬件等等）。这并不是master崩溃，但是计划维护必须去做。计划维护导致downtime，必须尽可能快的恢复。快速的master切换和优雅的阻塞写操作是必需的，MHA提供了这种方式。优雅的master切换， 0.5-2秒内阻塞写操作。在很多情况下0.5-2秒的downtime是可以接受的，并且即使不在计划维护窗口。这意味着当需要更换更快机器，升级高版本时，dba可以很容易采取动作。
5.master crash不会导致主从数据不一致性
当master crash后，MHA自动识别slave间relay logevents的不同，然后应用与不同的slave，最终所有slave都同步。结合通过半同步一起使用，几乎没有任何数据丢失。
其他高可用方案
6.MHA部署不影响当前环境设置
MHA最重要的一个设计理念就是尽可能使用简单。使用与5.0+以上主从环境，其他HA方案需要改变mysql部署设置，MHA不会让dba做这些部署配置，同步和半同步环境都可以用。启动/停止/升级/降级/安装/卸载 MHA都不用改变mysql主从（如启动/停止）。
当你需要升级MHA到新版本时，不需要停止mysql，仅仅更新HMA版本，然后重新启动MHAmanger即可。
MHA 支持包含5.0/5/1/5.5(应该也支持5.6，翻译文档时MHA开发者没更新对于5.6版本)。有些HA方案要求特定的mysql版本（如mysqlcluster，mysql with global transaction id 等）,而且你可能不想仅仅为了MasterHA而迁移应用。很多情况下，公司已经部署了许多传统的mysql应用，开发或dba不想花太多时间迁移到不同的存储引擎或新的特性（newer bleeding edge distributions 不知道这个是否该这么翻译）。
7.不增加服务器费用
MHA 包含MHA Manager和MHA node。MHA node运行在每台mysql服务器上，Manager可以单独部署一台机器，监控100+以上master，总服务器数量不会有太大增加。需要注意的是Manager也可以运行在slaves中的一台机器上。
8.性能无影响
当监控master，MHA只是几秒钟（默认3秒）发送ping包，不发送大的查询。主从复制性能不受影响
9.适用任何存储引擎
Mysql不仅仅适用于事务安全的innodb引擎，在主从中适用的引擎，MHA都可以适用。即使用遗留环境的mysiam引擎，不进行迁移，也可以用MHA。
安装配置方法
1、示例环境介绍
- centos 6.4 x64
- mysql-5.6.16-linux-glibc2.5-x86_64.tar.gz
- mha4mysql-manager-0.54.tar.gz
- mha4mysql-node-0.54.tar.gz
2、服务器说明
- masnager 192.168.216.50
- master 192.168.216.51
- slave 192.168.216.52
三台服务器都安装mysql，将manager作为管理节点
3、配置等价性
manager：
ssh-keyger -t rsa ssh-coyp-id -i /root/.ssh/id_rsa.pub root@192.168.216.50 ssh-coyp-id -i /root/.ssh/id_rsa.pub root@192.168.216.51 ssh-coyp-id -i /root/.ssh/id_rsa.pub root@192.168.216.52 ssh 192.168.216.50 date ssh 192.168.216.51 date ssh 192.168.216.52 date
master:
ssh-keyger -t rsa ssh-coyp-id -i /root/.ssh/id_rsa.pub root@192.168.216.50 ssh-coyp-id -i /root/.ssh/id_rsa.pub root@192.168.216.51 ssh-coyp-id -i /root/.ssh/id_rsa.pub root@192.168.216.52 ssh 192.168.216.50 date ssh 192.168.216.51 date ssh 192.168.216.52 date
slave:
ssh-keyger -t rsa ssh-coyp-id -i /root/.ssh/id_rsa.pub root@192.168.216.50 ssh-coyp-id -i /root/.ssh/id_rsa.pub root@192.168.216.51 ssh-coyp-id -i /root/.ssh/id_rsa.pub root@192.168.216.52 ssh 192.168.216.50 date ssh 192.168.216.51 date ssh 192.168.216.52 date
4、安装mysql
groupadd mysql useradd -g mysql -s /bin/nologin -M mysql mkdir -pv /data/mysql tar -zxvf mysql-5.6.16-linux-glibc2.5-x86_64.tar.gz mv mysql-5.6.16-linux-glibc2.5-x86_64 /usr/local/mysql cd /usr/local/mysql/script ./ mysql_install_db –user=mysql –basedir=/usr/local/mysql –datadair=/data/mysql
创建mysql配置文件
vim /usr/local/mysql/my.cnf
[mysql] # CLIENT # port = 3306 socket = /tmp/mysql.sock [mysqld] # GENERAL # user = mysql default-storage-engine = InnoDB socket = /tmp/mysql.sock pid-file = /data/mysql/mysql.pid # MyISAM # key-buffer-size = 32M myisam-recover = FORCE,BACKUP # SAFETY # max-allowed-packet = 16M max-connect-errors = 1000000 # DATA STORAGE # datadir = /data/mysql/ # BINARY LOGGING # server_id = 1 #不同服务器不一样 log-bin = /data/mysql/mysql-bin expire-logs-days = 14 sync-binlog = 1 # CACHES AND LIMITS # tmp-table-size = 32M max-heap-table-size = 32M query-cache-type = 0 query-cache-size = 0 max-connections = 500 thread-cache-size = 50 open-files-limit = 65535 table-definition-cache = 1024 table-open-cache = 2048 # INNODB # innodb-flush-method = O_DIRECT innodb-log-files-in-group = 2 innodb-log-file-size = 64M innodb-flush-log-at-trx-commit = 1 innodb-file-per-table = 1 innodb-buffer-pool-size = 592M # LOGGING # log-error = /data/mysql/mysql-error.log log-queries-not-using-indexes = 1 slow-query-log = 1 slow-query-log-file = /data/mysql/mysql-slow.log
5、配置权限
manager：
grant all privileges on *.* to root@'127.0.0.1' identified by 'root'; grant all privileges on *.* to root@'localhost' identified by 'root'; grant all privileges on *.* to root@'192.168.216.50' identified by 'root'; grant replication slave on *.* to slave@'192.168.216.50' identified by 'slave'; grant replication slave on *.* to slave@'192.168.216.51' identified by 'slave'; grant replication slave on *.* to slave@'192.168.216.52' identified by 'slave';
master:
grant all privileges on *.* to root@'127.0.0.1' identified by 'root'; grant all privileges on *.* to root@'localhost' identified by 'root'; grant all privileges on *.* to root@'192.168.216.50' identified by 'root'; grant replication slave on *.* to slave@'192.168.216.50' identified by 'slave'; grant replication slave on *.* to slave@'192.168.216.51' identified by 'slave'; grant replication slave on *.* to slave@'192.168.216.52' identified by 'slave';
slave:
grant all privileges on *.* to root@'127.0.0.1' identified by 'root'; grant all privileges on *.* to root@'localhost' identified by 'root'; grant all privileges on *.* to root@'192.168.216.50' identified by 'root'; grant all privileges on *.* to root@'192.168.216.51' identified by 'root'; grant replication slave on *.* to slave@'192.168.216.50' identified by 'slave'; grant replication slave on *.* to slave@'192.168.216.51' identified by 'slave'; grant replication slave on *.* to slave@'192.168.216.52' identified by 'slave';
6、安装依赖包
管理服务器manager需要安装以下全部
perl-Config-Tinyperl-Params-Validateperl-Parallel-ForkManagerperl-Log-Dispatch|- perl-MIME-Lite-3.027-2.el6.noarch.rpm |- perl-MIME-Types-1.28-2.el6.noarch.rpm |- perl-Email-Date-Format-1.002-5.el6.noarch.rpm |- perl-MailTools-2.04-4.el6.noarch.rpm |- perl-TimeDate-1.16-11.1.el6.noarch.rpm |- perl-Data-ShowTable-3.3-3.4.noarch.rpm|- perl-Mail-Sender-0.8.22-21.1.noarch.rpm |- perl-IO-Socket-SSL-1.31-2.el6.noarch.rpm |- perl-Net-LibIDN-0.12-3.el6.x86_64.rpm |- perl-Net-SSLeay-1.35-9.el6.x86_64.rpm |-perl-Win32API-Registry|- perl-Mail-Sendmail-0.79_16-4.2.noarch.rpm
rpm -ivh ncftp-debuginfo-3.2.3-1.3.x86_64.rpm rpm -ivh perl-Parallel-ForkManager-0.7.5-2.2.el6.rf.noarch.rpm rpm -ivh perl-Params-Validate-0.91-2.4.x86_64.rpm rpm -ivh perl-Config-Tiny-2.12-7.1.el6.noarch.rpm rpm -ivh perl-MIME-Types-1.28-2.el6.noarch.rpm rpm -ivh perl-Email-Date-Format-1.002-5.el6.noarch.rpm rpm -ivh perl-TimeDate-1.16-11.1.el6.noarch.rpm rpm -ivh perl-Data-ShowTable-3.3-3.4.noarch.rpm rpm -ivh perl-MailTools-2.04-4.el6.noarch.rpm rpm -ivh perl-MIME-Lite-3.027-2.el6.noarch.rpm rpm -ivh perl-Net-LibIDN-0.12-3.el6.x86_64.rpm rpm -ivh perl-Net-SSLeay-1.35-9.el6.x86_64.rpm rpm -ivh perl-IO-Socket-SSL-1.31-2.el6.noarch.rpm rpm -ivh perl-Mail-Sendmail-0.79_16-4.2.noarch.rpm rpm -ivh perl-Mail-Sender-0.8.22-21.1.noarch.rpm rpm -ivh perl-Log-Dispatch-2.22-7.3.noarch.rpm
如果安perl-DBD-MySQL-4.013-3.el6.x86_64.rpm在检查rep是报错则需要手动编译安装
tar -zxvf DBD-mysql-4.027.tar.gz cd DBD-mysql-4.0.27 perl Makefile.PL make && make install
节点服务器安装
rpm -ivh ncftp-debuginfo-3.2.3-1.3.x86_64.rpm rpm -ivh perl-DBD-MySQL-4.013-3.el6.x86_64.rpm
7、创建软连接
ln -s /usr/local/mysql/bin/mysqlbinlog /usr/bin/mysqlbinlog ln -s /usr/local/mysql/bin/mysql /usr/bin/mysql
导出mysql库搜索路径
vim /etc/ld.so.conf.d/mysql-x86_64.conf /usr/local/mysql/lib ldconfig
8、在所有服务器上安装mha4mysql-node-0.54.tar.gz
tar -zxvf mha4mysql-node-0.54.tar.gz cd mha4mysql-node-0.54 perl Makefile.PL make && make install
9、在管理服务上安装 mha4mysql-manager-0.54.tar.gz
tar -zxvf mha4mysql-manager-0.54.tar.gz cd mha4mysql-manager-0.54 perl Makefile.PL make && make install mkdir -pv /etc/masterha mkdir -pv /masterha/app1 cp samples/conf/* /etc/masterha cp samples/scripts/* /usr/local/bin
vim /etc/masterha/app1.cnf
[server default] manager_workdir=/masterha/app1 manager_log=/masterha/app1/manager.log user=root password=root ssh_user=root repl_user=slave repl_password=slave shutdown_script="" #master_ip_failover_script="/usr/local/bin/masterha_ip_failover" master_ip_online_change_script="/usr/local/bin/masterha_ip_failover " report_script="" [server1] hostname=192.168.216.50 master_binlog_dir="/data/mysql/" candidate_master=1 [server2] hostname=192.168.216.51 master_binlog_dir="/data/mysql/" candidate_master=1 [server3] hostname=192.168.216.52 master_binlog_dir="/data/mysql/" candidate_master=1
10、测试ssh连接
masterha_check_ssh –conf=/etc/masterha/app1.cnf
11、测试replication
masterha_check_repl –conf=/etc/masterha/app1.cnf
12、开启管理节点进程
masterha_manager –conf=/etc/masterha/app1.cnf
13、测试故障转移
关闭主库mysql，查看从库的的状态是否将同步ip切换到新的主库
14、设置故障转移的ip
vim /etc/masterha/app1.cnf
master_ip_failover_script="/usr/local/bin/masterha_ip_failover " master_ip_online_change_script="/usr/local/bin/masterha_ip_failover "
编辑故障转移脚本，将vip设置成192.168.216.100
vim /usr/local/bin/masterha_ip_failover
#!/usr/bin/env perluse 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 = '172.16.21.119/24'; # Virtual IPmy $vip = '192.168.216.100/24'; # Virtual IPmy $key = "1";my $ssh_start_vip = "/sbin/ifconfig eth0:$key $vip";my $ssh_stop_vip = "/sbin/ifconfig eth0:$key down"; 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" ) { # $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 "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" ) { # 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 "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"; `ssh $ssh_user\@cluster1 \" $ssh_start_vip \"`; exit 0; } else { &usage(); exit 1; }} # A simple system call that enable the VIP on the new mastersub start_vip() { `ssh $ssh_user\@$new_master_host \" $ssh_start_vip \"`;}# A simple system call that disable the VIP on the old_mastersub 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";}
测试脚本
/usr/local/bin/masterha_ip_failover –command=status –ssh_user=root –orig_master_host=192.168.216.51 –orig_master_ip=192.168.216.51 –orig_master_port=3306
虚拟ip要手动启动，在主库故障后会自动转移。
/usr/local/bin/masterha_ip_failover –command=start –ssh_user=root –orig_master_host=192.168.216.51 –orig_master_ip=192.168.216.51 –orig_master_port=3306 –new_master_host=192.168.216.51
测试ip故障转移：
关闭主库mysql，查看vip是否转移的新的主库上。
