利用mha实现mysql的主从自动切换
ssh免密连接：
[root@localhost etc]# ssh-keygen
[root@localhost etc]# ssh-copy-id -i /root/.ssh/id_rsa.pub [email protected] #免密登录对方的ssh 这的ip是对方的ip
[root@localhost etc]# vim /etc/ssh/ssh_config #关闭yes的询问
StrictHostKeyChecking no
**时间同步服务器：**随意找一台服务器作为时间的服务器，时间正确与错误本次实验没有要求，但是要一致
[root@localhost etc]# vim /etc/ntp.conf #时间服务器
restrict 127.0.0.1
restrict ::1
restrict 192.168.127.0 mask 255.255.255.0
server 127.127.1.0
时间客户端：参考
[root@localhost etc]# vim /etc/ntp.conf #该设置在下次启动才生效
server 192.168.153.7 iburst
[root@localhost etc]# ntpdate 192.168.127.7
**主服务器的配置：**172.18.251.133
[root@localhost etc]# /vim/etc/my.cnf
[mysqld]
server_id=2
datadir=/mysql/data
log_bin=/mysql/logbin/log
innodb_file_per_table
binlog_format=row
skip_name_resolve=1
socket=/var/lib/mysql/mysql.sock
MariaDB [(none)]> show master status;
+------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------+----------+--------------+------------------+
| log.000003 | 245 | | |
+------------+----------+--------------+------------------+
1 row in set (0.00 sec)
#建立主从同步的账号
MariaDB [(none)]> grant replication slave on *.* to repluser@'%' identified by 'centos';
Query OK, 0 rows affected (0.00 sec)
MariaDB [mysql]> grant all on *.* to mhauser@'%' identified by 'centos';
Query OK, 0 rows affected (0.00 sec)
**配置从服务器：**172.18.254.228 172.18.254.174
[mysqld]
server_id=24
datadir=/mysql/data
log_bin=/mysql/logbin/log
innodb_file_per_table
read_only=1
relay_log_purge=0
skip_name_resolve=1
socket=/var/lib/mysql/mysql.sock
MariaDB [(none)]> CHANGE MASTER TO
-> MASTER_HOST='172.18.251.133',
-> MASTER_USER='repluser',
-> MASTER_PASSWORD='centos',
-> MASTER_PORT=3306,
-> MASTER_LOG_FILE='log.000003',
-> MASTER_LOG_POS=245,
-> MASTER_CONNECT_RETRY=10;
Query OK, 0 rows affected (0.24 sec)
MariaDB [(none)]> start slave;
**mha服务器：**server#这个顺序决定这从服务器变为主的次序
[root@localhost etc]# vim /etc/mha/app1.conf
[server default]
user=mhauser #mha的账号
password=centos
manager_workdir=/data/mastermha/app1/
manager_log=/data/mastermha/app1/manager.log
master_binlog_dir=/mysql/logbin 设置master 保存binlog的位置，以便MHA可以找到master的日志
remote_workdir=/data/mastermha/app1/
ssh_user=root
repl_user=repluser
repl_password=centos
ping_interval=1
[server1]
hostname=192.168.153.17
candidate_master=1 #设置为候选master，如果设置该参数以后，发生主从切换以后将会将此从库提升为主库，即使这个主库不是集群中事件最新的slave
[server2]
hostname=192.168.153.27
candidate_master=1
[server3]
hostname=192.168.153.37
mha服务器测试：
[root@localhost etc]# masterha_check_ssh --conf=/etc/mha/app1.conf
.......
Wed Oct 17 09:55:42 2018 - [info] All SSH connection tests passed successfully.
[root@localhost etc]# masterha_check_repl --conf=/etc/mha/app1.conf
......
MySQL Replication Health is OK.
当主服务器损坏时，从服务器会自动变为主，read_only也会关闭，当主服务器再次修好时，会有主变为从其配置如下：
[root@localhost etc]# vim /etc/my.cnf
#增加以下两行
read_only=ON
relay_log_purge=0
[root@localhost etc]# systemctl restart mariadb.service
Master [(none)]> CHANGE MASTER TO
-> MASTER_HOST='172.15.254.228',
-> MASTER_USER='repluser',
-> MASTER_PASSWORD='centos',
-> MASTER_PORT=3306,
-> MASTER_LOG_FILE='slave-log.000003',
-> MASTER_LOG_POS=245,
-> MASTER_CONNECT_RETRY=10;
Query OK, 0 rows affected (0.05 sec)
Master [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)