MHA介紹
MHA是一位日本MySQL大牛用Perl寫的一套MySQL故障切換方案，來保證數據庫系統的高可用.在宕機的時間內（通常10—30秒內），完成故障切換，部署MHA，可避免主從一致性問題，節約購買新服務器的費用，不影響服務器性能，易安裝，不改變現有部署。
還支持在線切換，從當前運行master切換到一個新的master上面，只需要很短的時間（0.5-2秒內），此時僅僅阻塞寫操作，并不影響讀操作，便于主機硬件維護。
在有高可用，數據一致性要求的系統上，MHA 提供了有用的功能，幾乎無間斷的滿足維護需要。
優點：
1.master自動監控和故障轉移
在當前已存在的主從復制環境中，MHA可以監控master主機故障，并且故障自動轉移。
即使有一些slave沒有接受新的relay log events，MHA也會從最新的slave自動識別差異的relay log events，并apply差異的event到其他slaves。因此所有的slave都是一致的。MHA秒級別故障轉移（9-12秒監測到主機故障，任選7秒鐘關閉電源主機避免腦裂，接下來apply差異relay logs，注冊到新的master，通常需要時間10-30秒即total downtime）。另外，在配置文件里可以配置一個slave優先成為master。因為MHA修復了slave之間的一致性，dba就不用去處理一致性問題。
當遷移新的master之后，并行恢復其他slave。即使有成千上萬的slave,也不會影響恢復master時間，slave也很快完成。
DeNA公司在150+主從環境中用MHA。當其中一個master崩潰，MHA4秒完成故障轉移，這是主動/被動集群解決方案無法完成的。
2.互動(手動)master故障轉移
MHA可以用來只做故障轉移，而不監測master，MHA只作為故障轉移的交互。
3.非交互式故障轉移
非交互式的故障轉移也提供（不監控master，自動故障轉移）。這個特性很有用，特別是你已經安裝了其他軟件監控master。比如，用Pacemaker(Heartbeat)監測master故障和vip接管，用MHA故障轉移和slave提升。
4.在線切換master到不同主機
在很多情況下，有必要將master轉移到其他主機上（如替換raid控制器，提升master機器硬件等等）。這并不是master崩潰，但是計劃維護必須去做。計劃維護導致downtime，必須盡可能快的恢復。快速的master切換和優雅的阻塞寫操作是必需的，MHA提供了這種方式。優雅的master切換， 0.5-2秒內阻塞寫操作。在很多情況下0.5-2秒的downtime是可以接受的，并且即使不在計劃維護窗口。這意味著當需要更換更快機器，升級高版本時，dba可以很容易采取動作。
5.master crash不會導致主從數據不一致性
當master crash后，MHA自動識別slave間relay logevents的不同，然后應用與不同的slave，最終所有slave都同步。結合通過半同步一起使用，幾乎沒有任何數據丟失。
其他高可用方案
6.MHA部署不影響當前環境設置
MHA最重要的一個設計理念就是盡可能使用簡單。使用與5.0+以上主從環境，其他HA方案需要改變mysql部署設置，MHA不會讓dba做這些部署配置，同步和半同步環境都可以用。啟動/停止/升級/降級/安裝/卸載 MHA都不用改變mysql主從（如啟動/停止）。
當你需要升級MHA到新版本時，不需要停止mysql，僅僅更新HMA版本，然后重新啟動MHAmanger即可。
MHA 支持包含5.0/5/1/5.5(應該也支持5.6，翻譯文檔時MHA開發者沒更新對于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）,而且你可能不想僅僅為了MasterHA而遷移應用。很多情況下，公司已經部署了許多傳統的mysql應用，開發或dba不想花太多時間遷移到不同的存儲引擎或新的特性（newer bleeding edge distributions 不知道這個是否該這么翻譯）。
7.不增加服務器費用
MHA 包含MHA Manager和MHA node。MHA node運行在每臺mysql服務器上，Manager可以單獨部署一臺機器，監控100+以上master，總服務器數量不會有太大增加。需要注意的是Manager也可以運行在slaves中的一臺機器上。
8.性能無影響
當監控master，MHA只是幾秒鐘（默認3秒）發送ping包，不發送大的查詢。主從復制性能不受影響
9.適用任何存儲引擎
Mysql不僅僅適用于事務安全的innodb引擎，在主從中適用的引擎，MHA都可以適用。即使用遺留環境的mysiam引擎，不進行遷移，也可以用MHA。
安裝配置方法
1、示例環境介紹
- 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、服務器說明
- masnager 192.168.216.50
- master 192.168.216.51
- slave 192.168.216.52
三臺服務器都安裝mysql，將manager作為管理節點
3、配置等價性
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、安裝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
創建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 #不同服務器不一樣 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、配置權限
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、安裝依賴包
管理服務器manager需要安裝以下全部
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在檢查rep是報錯則需要手動編譯安裝
tar -zxvf DBD-mysql-4.027.tar.gz cd DBD-mysql-4.0.27 perl Makefile.PL make && make install
節點服務器安裝
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、創建軟連接
ln -s /usr/local/mysql/bin/mysqlbinlog /usr/bin/mysqlbinlog ln -s /usr/local/mysql/bin/mysql /usr/bin/mysql
導出mysql庫搜索路徑
vim /etc/ld.so.conf.d/mysql-x86_64.conf /usr/local/mysql/lib ldconfig
8、在所有服務器上安裝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、在管理服務上安裝 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、測試ssh連接
masterha_check_ssh –conf=/etc/masterha/app1.cnf
11、測試replication
masterha_check_repl –conf=/etc/masterha/app1.cnf
12、開啟管理節點進程
masterha_manager –conf=/etc/masterha/app1.cnf
13、測試故障轉移
關閉主庫mysql，查看從庫的的狀態是否將同步ip切換到新的主庫
14、設置故障轉移的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 "
編輯故障轉移腳本，將vip設置成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";}
測試腳本
/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
虛擬ip要手動啟動，在主庫故障后會自動轉移。
/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
測試ip故障轉移：
關閉主庫mysql，查看vip是否轉移的新的主庫上。
