The principle and function of 0, MHA's
1), monitoring node (all nodes obtain information via the configuration file)
System, network
From the master state
2) election of the main policies
1) If it is determined from the library (position or gtid), there is difference data, the closest to the slave master, become the main alternatives;
2) If it is determined from the library (position or gtid) data match the installation profile configuration server sequentially selected (default)
3) If the right to set the weight (candidate_master = 1), according to their weights enforce the alternate master
1), by default, if a slave relay logs behind the master 100M of it, even if it will not have the right to re-elect it;
2) If check_repl_delay = 0, even if the log far behind, which is also forced to select an alternative primary
3) Data compensation strategies
1) When the ssh connectable, on the primary database gtid or position number, the binary log holding immediately from the library and applied to each slave node (save_binary_logs);
2) When the connection can not ssh, from the comparison between the difference relaylog library (apply_diff_relay_logs)
4） Failover
The main alternative identity switch, to provide services outside the remainder confirm the new master-slave relationship from the library and new main library
5) transparent to the application (VIP)
6) notification mechanism (send_report)
7) the second compensation data (binlog_server)
8) healing (to be developed in .......)
1, 2 the MHA from the main environment, from the environment to ensure that the main normal
Download mha-node and mha-manage
Download: https://github.com/yoshinorim/mha4mysql-node/releases
2, the configuration from the master trust between ssh
ssh-keygen -t rsa -P ' '
ssh-copy-id
Interoperable nodes in three mutual authentication and
3, create a soft link
ln -s /app/mysql/bin/mysqlbinlog /usr/bin/mysqlbinlog
ln -s /app/mysql/bin/mysql /usr/bin/mysql
4, the software installation node (three nodes are installed)
yum install perl-DBD-MySQL -y
yum localinstall mha4mysql-node-0.58-0.el7.centos.noarch.rpm
5, select one of the servers as the server manager software and install the following
yum install -y perl-Config-Tiny perl-Log-Dispatch perl-Parallel-ForkManger perl-Time-HiRes
Compiler need to install the following libraries (yum install perl-CPAN * -y) installation
yum localinstall mha4mysql-manager-0.58-0.el7.centos.noarch.rpm -y
6, MHA create user-specific monitoring and management (creation can be directly in the main library)
grant all privileges on *.* to 'mha'@'192.168.1.%' identified by '123';
flush privileges;
7, viewed on three different nodes mha whether the user is successful
select user,host from mysql.user;
8, the configuration manager node configuration file manager
Create a configuration directory
mkdir -p /etc/mha
Create a log directory
mkdir -p / var / log / MHA
Edit the configuration file mha
[server default]
manager_log=/var/log/mha/app1/manager
manager_workdir=/var/log/mha/app1
master_binlog_dir=/data/mysql/binlog
user=mha
password=mha
ping_interval=2
repl_password=123.com
repl_user=repl
ssh_user=root
[server1]
hostname=192.168.1.130
port=3306
[server2]
hostname=192.168.1.141
port=3306
[server3]
hostname=192.168.1.145
port=3306
9, using the built-in command mha tool to verify ssh trust (all ok, shows normal environment)
master_check_ssh --conf=/etc/mha/app1.conf
10, verify that the master copy from
master_check_repl --conf=/etc/mha/app1.conf
11, start manager
nohup masterha_manager --conf = / etc / mha / app1.cnf --remove_dead_master_conf --ignore_last_failover </ dev / null> /var/log/mha/app1/manager.log 2> & 1 &
verify the success of start
masterha_check_status --conf=/etc/mha/app1.cnf