MySQL集群搭建(5)-MHA高可用架构
1 概述
1.1 MHA 简介
MHA - Master High Availability 是由 Perl 实现的一款高可用程序，出现故障时，MHA 以最小的停机时间(通常10-30秒)执行 master 的故障转移以及 slave 的升级。MHA 可防止复制一致性问题，并且易于安装，不需要改变现有部署。
MHA 由MHA manager和MHA node组成, MHA manager是一个监控管理程序，用于监控MySQL master状态; MHA node是具有故障转移的工具脚本，如解析 MySQL 二进制/中继日志，传输应用事件到Slave, MHA node在每个MySQL服务器上运行。
MHA manager调用MHA node工具脚本的方式是SSH到主机上然后执行命令，所以各节点需要做等效验证。
1.2 MHA 怎么保证数据不丢失
当Master宕机后，MHA会尝试保存宕机Master的二进制日志，然后自动判断MySQL集群中哪个实例的中继日志是最新的，并将有最新日志的实例的差异日志传到其他实例补齐，从而实现所有实例数据一致。然后把宕机Master的二进制日志应用到选定节点，并提升为 Master。
具体流程如下：
- 尝试从宕机
Master中保存二进制日志 - 找到含有最新中继日志的
Slave - 把最新中继日志应用到其他实例，实现各实例数据一致
- 应用从
Master保存的二进制日志事件 - 提升一个
Slave为Master - 其他
Slave向该新Master同步
从切换流程流程可以看到，如果宕机Master主机无法SSH登录，那么第一步就没办法实现，对于MySQL5.5以前的版本，数据还是有丢失的风险。对于5.5后的版本，开启半同步复制后，真正有助于避免数据丢失，半同步复制保证至少一个 （不是所有）slave 在 master 提交时接收到二进制日志事件。因此，对于可以处理一致性问题的MHA 可以实现"几乎没有数据丢失"和"从属一致性"。
1.3 MHA 优点和限制
优点
- 开源，用
Perl编写 - 方案成熟，故障切换时，
MHA会做日志补齐操作，尽可能减少数据丢失，保证数据一 - 部署不需要改变现有架构
限制
- 各个节点要打通
SSH信任，有一定的安全隐患 - 没有
Slave的高可用 - 自带的脚本不足，例如虚IP配置需要自己写命令或者依赖其他软件
- 需要手动清理中继日志
1.4 MHA 常用两种复制配置
单 master，多 slave
M(RW)
|
+-------+-------+
S1(R) S2(R) S3(R)
这种复制方式非常常见，当Master宕机时，MHA会选一个日志最新的主机升级为Master, 如果不希望个节点成为Master，把no_master设为1就可以。
多 master, 多 slave
M(RW)----M2(R, candidate_master=1)
|
+-------+-------+
S1(R) S2(R)
双主结构也是常见的复制模式，如果当前Master崩溃, MHA会选择只读Master成为新的Master
2 数据库环境准备
本次演示使用复制方式是主主从，主主从数据库搭建方式参考以前文章
2.1 节点信息
| IP | 系统 | 端口 | MySQL版本 | 节点 | 读写 | 说明 |
|---|---|---|---|---|---|---|
| 10.0.0.247 | Centos6.5 | 3306 | 5.7.9 | Master | 读写 | 主节点 |
| 10.0.0.248 | Centos6.5 | 3306 | 5.7.9 | Standby | 只读,可切换为读写 | 备主节点 |
| 10.0.0.249 | Centos6.5 | 3306 | 5.7.9 | Slave | 只读 | 从节点 |
| 10.0.0.24 | Centos6.5 | - | - | manager | - | MHA Manager |
| 10.0.0.237 | - | - | - | - | - | VIP |
2.2 架构图
2.3 参考配置
Master1
[client]
port = 3306
default-character-set=utf8mb4
socket = /data/mysql_db/test_db/mysql.sock
[mysqld]
datadir = /data/mysql_db/test_db
basedir = /usr/local/mysql57
tmpdir = /tmp
socket = /data/mysql_db/test_db/mysql.sock
pid-file = /data/mysql_db/test_db/mysql.pid
skip-external-locking = 1
skip-name-resolve = 1
port = 3306
server_id = 2473306
default-storage-engine = InnoDB
character-set-server = utf8mb4
default_password_lifetime=0
auto_increment_offset = 1
auto_increment_increment = 2
#### log ####
log_timestamps=system
log_bin = /data/mysql_log/test_db/mysql-bin
log_bin_index = /data/mysql_log/test_db/mysql-bin.index
binlog_format = row
relay_log_recovery=ON
relay_log=/data/mysql_log/test_db/mysql-relay-bin
relay_log_index=/data/mysql_log/test_db/mysql-relay-bin.index
log_error = /data/mysql_log/test_db/mysql-error.log
#### replication ####
log_slave_updates = 1
replicate_wild_ignore_table = information_schema.%,performance_schema.%,sys.%
#### semi sync replication settings #####
plugin_dir=/usr/local/mysql57/lib/plugin
plugin_load = "rpl_semi_sync_master=semisync_master.so;rpl_semi_sync_slave=semisync_slave.so"
loose_rpl_semi_sync_master_enabled = 1
loose_rpl_semi_sync_slave_enabled = 1
Master2
[client]
port = 3306
default-character-set=utf8mb4
socket = /data/mysql_db/test_db/mysql.sock
[mysqld]
datadir = /data/mysql_db/test_db
basedir = /usr/local/mysql57
tmpdir = /tmp
socket = /data/mysql_db/test_db/mysql.sock
pid-file = /data/mysql_db/test_db/mysql.pid
skip-external-locking = 1
skip-name-resolve = 1
port = 3306
server_id = 2483306
default-storage-engine = InnoDB
character-set-server = utf8mb4
default_password_lifetime=0
auto_increment_offset = 2
auto_increment_increment = 2
#### log ####
log_timestamps=system
log_bin = /data/mysql_log/test_db/mysql-bin
log_bin_index = /data/mysql_log/test_db/mysql-bin.index
binlog_format = row
relay_log_recovery=ON
relay_log=/data/mysql_log/test_db/mysql-relay-bin
relay_log_index=/data/mysql_log/test_db/mysql-relay-bin.index
log_error = /data/mysql_log/test_db/mysql-error.log
#### replication ####
log_slave_updates = 1
replicate_wild_ignore_table = information_schema.%,performance_schema.%,sys.%
#### semi sync replication settings #####
plugin_dir=/usr/local/mysql57/lib/plugin
plugin_load = "rpl_semi_sync_master=semisync_master.so;rpl_semi_sync_slave=semisync_slave.so"
loose_rpl_semi_sync_master_enabled = 1
loose_rpl_semi_sync_slave_enabled = 1
Slave
[client]
port = 3306
default-character-set=utf8mb4
socket = /data/mysql_db/test_db/mysql.sock
[mysqld]
datadir = /data/mysql_db/test_db
basedir = /usr/local/mysql57
tmpdir = /tmp
socket = /data/mysql_db/test_db/mysql.sock
pid-file = /data/mysql_db/test_db/mysql.pid
skip-external-locking = 1
skip-name-resolve = 1
port = 3306
server_id = 2493306
default-storage-engine = InnoDB
character-set-server = utf8mb4
default_password_lifetime=0
read_only=1
#### log ####
log_timestamps=system
log_bin = /data/mysql_log/test_db/mysql-bin
log_bin_index = /data/mysql_log/test_db/mysql-bin.index
binlog_format = row
relay_log_recovery=ON
relay_log=/data/mysql_log/test_db/mysql-relay-bin
relay_log_index=/data/mysql_log/test_db/mysql-relay-bin.index
log_error = /data/mysql_log/test_db/mysql-error.log
#### replication ####
log_slave_updates = 1
replicate_wild_ignore_table = information_schema.%,performance_schema.%,sys.%
#### semi sync replication settings #####
plugin_dir=/usr/local/mysql57/lib/plugin
plugin_load = "rpl_semi_sync_master=semisync_master.so;rpl_semi_sync_slave=semisync_slave.so"
loose_rpl_semi_sync_master_enabled = 1
loose_rpl_semi_sync_slave_enabled = 1
3 安装配置 MHA
3.1 下载 MHA
进入 MHA 下载页面 Downloads, 下载Manager和Node节点安装包，由于我的服务器是centos6，所以下载了MHA Manager 0.56 rpm RHEL6和MHA Node 0.56 rpm RHEL6
3.2 安装 MHA
Node安装
在所有主机(包括Manager)上执行
# 安装依赖
yum install perl perl-devel perl-DBD-MySQL
# 安装 node 工具
rpm -ivh mha4mysql-node-0.56-0.el6.noarch.rpm
Manager安装
在 Manager 主机上执行
# 安装依赖
yum install -y perl perl-devel perl-DBD-MySQL perl-Config-Tiny perl-Log-Dispatch perl-Parallel-ForkManager perl-Time-HiRes
# 安装 manager
rpm -ivh mha4mysql-manager-0.56-0.el6.noarch.rpm
3.3 创建 MHA 管理用户
管理用户需要执行一些数据库管理命令包括STOP SLAVE, CHANGE MASTER, RESET SLAVE
create user mha_manager@'%' identified by 'mha_manager';
grant all on *.* to mha_manager@'%';
flush privileges;
3.4 增加 MySQL 用户 sudo 权限
配置 VIP 需要有 sudo 权限
打开/etc/sudoers文件, 增加一条
root ALL=(ALL) ALL
# 这个是增加的
mysql ALL=(ALL) NOPASSWD: ALL
然后把Defaults requiretty注释掉
# Defaults requiretty
3.5 配置各主机免密码登陆
所有主机执行
# 进入 mysql 用户
su - mysql
# 生成密钥对, 执行命令，然后按回车
ssh-keygen -t rsa
# 复制公钥到相应主机
ssh-copy-id mysql@10.0.0.247
ssh-copy-id mysql@10.0.0.248
ssh-copy-id mysql@10.0.0.249
ssh-copy-id mysql@10.0.1.24
3.6 配置 Manager
新建/etc/masterha目录，我们把配置文件放到这里
mkdir /etc/masterha
创建配置文件/etc/masterha/app1.cnf, 写上配置
[server default]
manager_workdir=/etc/masterha # 设置 manager 的工作目录, 可以自己调整
manager_log=/etc/masterha/manager.log # 设置 manager 的日志文件
master_binlog_dir=/data/mysql_log/test_db # 设置 master binlog 的日志的位置
master_ip_failover_script= /etc/masterha/script/master_ip_failover # 设置自动 failover 时的切换脚本, 脚本参考附件
master_ip_online_change_script= /etc/masterha/script/master_ip_online_change # 设置手动切换时执行的切换脚本, 脚本参考附件
user=mha_manager # 设置管理用户, 用来监控、配置 MySQL(STOP SLAVE, CHANGE MASTER, RESET SLAVE), 默认为 root
password=mha_manager # 设置管理用户密码
repl_user=repl # 设置复制环境中的复制用户名
repl_password=repl # 设置复制用户的密码
ping_interval=1 # 发送 ping 包的时间间隔，三次没有回应就自动进行 failover
remote_workdir=/tmp # 设置远端 MySQL 的工作目录
report_script=/etc/masterha/script/send_report # 设置发生切换后执行的脚本
# 检查脚本
secondary_check_script= /usr/bin/masterha_secondary_check-s 10.0.0.247 -s 10.0.0.248
shutdown_script="" #设置故障发生后关闭故障主机脚本(可以用于防止脑裂)
ssh_user=mysql #设置 ssh 的登录用户名
[server1]
hostname=10.0.0.247
port=3306
[server2]
hostname=10.0.0.248
port=3306
candidate_master=1 # 设置为候选 master, 如果发生宕机切换，会把该节点设为新 Master，即使它不是数据最新的节点
check_repl_delay=0 # 默认情况下，一个 Slave 落后 Master 100M 的中继日志，MHA 不会选择它作为新的 Master，因为这对于 Slave 恢复数据要很长时间，check_repl_delay=0 的时候会忽略延迟，可以和 candidate_master=1 配合用
[server3]
hostname=10.0.0.249
port=3306
no_master=1 # 从不将这台主机升级为 Master
ignore_fail=1 # 默认情况下，如果有 Slave 节点挂了， 就不进行切换，设置 ignore_fail=1 可以忽然它
创建配置文件/etc/masterha/app2.cnf, 以备用Master 为 Master, 方便切换后启动MHA
[server default]
manager_workdir=/etc/masterha # 设置 manager 的工作目录, 可以自己调整
manager_log=/etc/masterha/manager.log # 设置 manager 的日志文件
master_binlog_dir=/data/mysql_log/test_db # 设置 master binlog 的日志的位置
master_ip_failover_script= /etc/masterha/script/master_ip_failover # 设置自动 failover 时的切换脚本
master_ip_online_change_script= /etc/masterha/script/master_ip_online_change # 设置手动切换时执行的切换脚本
user=mha_manager # 设置管理用户, 用来监控、配置 MySQL(STOP SLAVE, CHANGE MASTER, RESET SLAVE), 默认为 root
password=mha_manager # 设置管理用户密码
repl_user=repl # 设置复制环境中的复制用户名
repl_password=repl # 设置复制用户的密码
ping_interval=1 # 发送 ping 包的时间间隔，三次没有回应就自动进行 failover
remote_workdir=/tmp # 设置远端 MySQL 的工作目录
report_script=/etc/masterha/script/send_report # 设置发生切换后执行的脚本
# 检查脚本
secondary_check_script= /usr/bin/masterha_secondary_check -s 10.0.0.248 -s 10.0.0.247
shutdown_script="" #设置故障发生后关闭故障主机脚本(可以用于防止脑裂)
ssh_user=mysql #设置 ssh 的登录用户名
[server1]
hostname=10.0.0.248
port=3306
[server2]
hostname=10.0.0.247
port=3306
candidate_master=1 # 设置为候选 master, 如果发生宕机切换，会把该节点设为新 Master，即使它不是数据最新的节点
check_repl_delay=0 # 默认情况下，一个 Slave 落后 Master 100M 的中继日志，MHA 不会选择它作为新的 Master，因为这对于 Slave 恢复数据要很长时间，check_repl_delay=0 的时候会忽略延迟，可以和 candidate_master=1 配合用
[server3]
hostname=10.0.0.249
port=3306
no_master=1 # 从不将这台主机升级为 Master
ignore_fail=1 # 默认情况下，如果有 Slave 节点挂了， 就不进行切换，设置 ignore_fail=1 可以忽然它
注意：使用的时候去掉注释
3.7 配置切换脚本
管理 VIP 方式
MHA管理VIP有两种方案，一种是使用Keepalived，另一种是自己写命令实现增删VIP，由于Keepalived容易受到网络波动造成VIP切换，而且无法在多实例机器上使用，所以建议写脚本管理VIP。
当前主机的网卡是eth0, 可以通过下列命令增删 VIP
up VIP
sudo /sbin/ifconfig eth0:1 10.0.0.237 netmask 255.255.255.255
down VIP
sudo /sbin/ifconfig eth0:1 down
配置切换脚本
master_ip_failover , master_ip_online_change和send_report脚本在附录里面
更改 mysql 配置
MHA的检测比较严格，所以我们把除Master外的节点设为read_only, 有必要可以写进配置文件里面
# mysql shell
set global read_only=1;
MHA需要使用中继日志来实现数据一致性，所以所有节点要设置不自动清理中继日志
# mysql shell
set global relay_log_purge=0;
也可以写入配置文件
# my.cnf
relay_log_purge=0
MHA 常用命令
Manager
masterha_check_ssh 检查 MHA 的 SSH 配置状况
masterha_check_repl 检查 MySQL 复制状况
masterha_manger 启动 MHA
masterha_stop 停止 MHA
masterha_check_status 检测当前 MHA 运行状态
masterha_master_monitor 检测 master 是否宕机
masterha_master_switch 手动故障转移
masterha_conf_host 添加或删除配置的 server 信息
Node
save_binary_logs 保存 master 的二进制日志
apply_diff_relay_logs 对比识别中继日志的差异部分
purge_relay_logs 清除中继日志(MHA中继日志需要使用这个命令清除)
命令的使用方法可以通过执行命令 --help 得到
验证 SSH 是否成功、主从状态是否正常
在 manager 节点执行 masterha_check_ssh --conf=/etc/masterha/app1.cnf 检测SSH状态，下面是执行结果
[mysql@chengqm ~]$ masterha_check_ssh --conf=/etc/masterha/app1.cnf
Thu Dec 20 19:47:18 2018 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Thu Dec 20 19:47:18 2018 - [info] Reading application default configuration from /etc/masterha/app1.cnf..
Thu Dec 20 19:47:18 2018 - [info] Reading server configuration from /etc/masterha/app1.cnf..
Thu Dec 20 19:47:18 2018 - [info] Starting SSH connection tests..
Thu Dec 20 19:47:19 2018 - [debug]
Thu Dec 20 19:47:18 2018 - [debug] Connecting via SSH from mysql@10.0.0.247(10.0.0.247:22) to mysql@10.0.0.248(10.0.0.248:22)..
Thu Dec 20 19:47:19 2018 - [debug] ok.
Thu Dec 20 19:47:19 2018 - [debug] Connecting via SSH from mysql@10.0.0.247(10.0.0.247:22) to mysql@10.0.0.249(10.0.0.249:22)..
Thu Dec 20 19:47:19 2018 - [debug] ok.
Thu Dec 20 19:47:19 2018 - [debug]
Thu Dec 20 19:47:19 2018 - [debug] Connecting via SSH from mysql@10.0.0.248(10.0.0.248:22) to mysql@10.0.0.247(10.0.0.247:22)..
Thu Dec 20 19:47:19 2018 - [debug] ok.
Thu Dec 20 19:47:19 2018 - [debug] Connecting via SSH from mysql@10.0.0.248(10.0.0.248:22) to mysql@10.0.0.249(10.0.0.249:22)..
Thu Dec 20 19:47:19 2018 - [debug] ok.
Thu Dec 20 19:47:20 2018 - [debug]
Thu Dec 20 19:47:19 2018 - [debug] Connecting via SSH from mysql@10.0.0.249(10.0.0.249:22) to mysql@10.0.0.247(10.0.0.247:22)..
Thu Dec 20 19:47:20 2018 - [debug] ok.
Thu Dec 20 19:47:20 2018 - [debug] Connecting via SSH from mysql@10.0.0.249(10.0.0.249:22) to mysql@10.0.0.248(10.0.0.248:22)..
Thu Dec 20 19:47:20 2018 - [debug] ok.
Thu Dec 20 19:47:20 2018 - [info] All SSH connection tests passed successfully.
在 manager 节点执行 masterha_check_repl --conf=/etc/masterha/app1.cnf 检测同步状态，下面是执行结果
[mysql@chengqm ~]$ masterha_check_repl --conf=/etc/masterha/app1.cnf
Thu Dec 20 20:05:03 2018 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Thu Dec 20 20:05:03 2018 - [info] Reading application default configuration from /etc/masterha/app1.cnf..
Thu Dec 20 20:05:03 2018 - [info] Reading server configuration from /etc/masterha/app1.cnf..
Thu Dec 20 20:05:03 2018 - [info] MHA::MasterMonitor version 0.56.
Thu Dec 20 20:05:03 2018 - [info] Multi-master configuration is detected. Current primary(writable) master is 10.0.0.247(10.0.0.247:3306)
Thu Dec 20 20:05:03 2018 - [info] Master configurations are as below:
Master 10.0.0.247(10.0.0.247:3306), replicating from 10.0.0.248(10.0.0.248:3306)
Master 10.0.0.248(10.0.0.248:3306), replicating from 10.0.0.247(10.0.0.247:3306), read-only
================ 省略 ==================
Thu Dec 20 20:05:08 2018 - [info] /etc/masterha/script/master_ip_failover --command=status --ssh_user=mysql --orig_master_host=10.0.0.247 --orig_master_ip=10.0.0.247 --orig_master_port=3306
Thu Dec 20 20:05:08 2018 - [info] OK.
Thu Dec 20 20:05:08 2018 - [warning] shutdown_script is not defined.
Thu Dec 20 20:05:08 2018 - [info] Got exit code 0 (Not master dead).
MySQL Replication Health is OK.
出现 MySQL Replication Health is OK. 表示成功
如果出现Failed to get master_ip_failover_script status with return code 255:0这个错误，就注释掉master_ip_failover脚本的FIXME_xxx
注意：要想正常运行，系统路径必须要有 mysqlbinlog 和 mysql 命令
4 启动和测试
4.1 启动
使用脚本管理 VIP 不会自动设置 VIP，所以先手动在 Master 设置 VIP
[root@cluster01 ~]# /sbin/ifconfig eth0:1 10.0.0.237 netmask 255.255.255.255
[root@cluster01 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr FA:16:3E:DE:80:33
inet addr:10.0.0.247 Bcast:10.0.255.255 Mask:255.255.0.0
inet6 addr: fe80::f816:3eff:fede:8033/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:17333247 errors:0 dropped:0 overruns:0 frame:0
TX packets:5472004 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1476157398 (1.3 GiB) TX bytes:1064253754 (1014.9 MiB)
eth0:1 Link encap:Ethernet HWaddr FA:16:3E:DE:80:33
inet addr:10.0.0.237 Bcast:10.0.0.237 Mask:255.255.255.255
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
...
启动 MHA Manager
[mysql@chengqm ~]$ nohup /usr/bin/masterha_manager --conf=/etc/masterha/app1.cnf --ignore_last_failover &
[1] 21668
--ignore_last_failover忽略上次切换。MHA每次故障切换后都会生成一个app1.failover.complete这样的文件，如果不加这个参数，需要删除这个文件才能再次启动
检查启动日志
[mysql@chengqm ~]$ tail -18 /etc/masterha/manager.log
Fri Dec 21 13:56:39 2018 - [info]
10.0.0.247(10.0.0.247:3306) (current master)
+--10.0.0.248(10.0.0.248:3306)
+--10.0.0.249(10.0.0.249:3306)
Fri Dec 21 13:56:39 2018 - [info] Checking master_ip_failover_script status:
Fri Dec 21 13:56:39 2018 - [info] /etc/masterha/script/master_ip_failover --command=status --ssh_user=mysql --orig_master_host=10.0.0.247 --orig_master_ip=10.0.0.247 --orig_master_port=3306
VIP Command: start=sudo /sbin/ifconfig eth0:1 10.0.0.237 netmask 255.255.255.255 stop=sudo /sbin/ifconfig eth0:1 down
Check script.. OK
Fri Dec 21 13:56:39 2018 - [info] OK.
Fri Dec 21 13:56:39 2018 - [warning] shutdown_script is not defined.
Fri Dec 21 13:56:39 2018 - [info] Set master ping interval 1 seconds.
Fri Dec 21 13:56:39 2018 - [info] Set secondary check script: /usr/bin/masterha_secondary_check -s 10.0.0.247 -s 10.0.0.248
Fri Dec 21 13:56:39 2018 - [info] Starting ping health check on 10.0.0.247(10.0.0.247:3306)..
Fri Dec 21 13:56:39 2018 - [info] Ping(SELECT) succeeded, waiting until MySQL doesn't respond..
日志中显示 Ping(SELECT) succeeded, waiting until MySQL doesn't respond 表示启动成功
如果查看Master的general日志，会发现MHA不断执行SELECT 1 As Value检查命令
4.2 失效转移
我们模拟Master数据库宕机的情况
[root@cluster01 ~]# ps -ef | grep mysql
mysql 20061 1 0 11:19 pts/0 00:00:00 /bin/sh /usr/local/mysql57/bin/mysqld_safe --defaults-file=/data/mysql_db/test_db/my.cnf --datadir=/data/mysql_db/test_db --pid-file=/data/mysql_db/test_db/mysql.pid
mysql 20494 20061 0 11:19 pts/0 00:00:21 /usr/local/mysql57/bin/mysqld --defaults-file=/data/mysql_db/test_db/my.cnf --basedir=/usr/local/mysql57 --datadir=/data/mysql_db/test_db --plugin-dir=/usr/local/mysql57/lib/plugin --log-error=/data/mysql_log/test_db/mysql-error.log --pid-file=/data/mysql_db/test_db/mysql.pid --socket=/data/mysql_db/test_db/mysql.sock --port=3306
[root@cluster01 ~]# kill -9 20061 20494
查看MHA日志可以看到整个切换过程
Fri Dec 21 14:04:49 2018 - [warning] Got error on MySQL select ping: 2006 (MySQL server has gone away)
Fri Dec 21 14:04:49 2018 - [info] Executing secondary network check script: /usr/bin/masterha_secondary_check -s 10.0.0.247 -s 10.0.0.248 --user=mysql --master_host=10.0.0.247 --master_ip=10.0.0.247 --master_port=3306 --master_user=mha_manager --master_password=mha_manager --ping_type=SELECT
Fri Dec 21 14:04:49 2018 - [info] Executing SSH check script: save_binary_logs --command=test --start_pos=4 --binlog_dir=/data/mysql_log/test_db --output_file=/tmp/save_binary_logs_test --manager_version=0.56 --binlog_prefix=mysql-bin
Monitoring server 10.0.0.247 is reachable, Master is not reachable from 10.0.0.247. OK.
Fri Dec 21 14:04:49 2018 - [info] HealthCheck: SSH to 10.0.0.247 is reachable.
Monitoring server 10.0.0.248 is reachable, Master is not reachable from 10.0.0.248. OK.
Fri Dec 21 14:04:49 2018 - [info] Master is not reachable from all other monitoring servers. Failover should start.
=============== 省略 ================
Fri Dec 21 14:04:52 2018 - [info] Forcing shutdown so that applications never connect to the current master..
Fri Dec 21 14:04:52 2018 - [info] Executing master IP deactivation script:
Fri Dec 21 14:04:52 2018 - [info] /etc/masterha/script/master_ip_failover --orig_master_host=10.0.0.247 --orig_master_ip=10.0.0.247 --orig_master_port=3306 --command=stopssh --ssh_user=mysql
VIP Command: start=sudo /sbin/ifconfig eth0:1 10.0.0.237 netmask 255.255.255.255 stop=sudo /sbin/ifconfig eth0:1 down
Disabling the VIP on old master: 10.0.0.247
SIOCSIFFLAGS: Cannot assign requested address
Fri Dec 21 14:04:52 2018 - [info] done.
=============== 省略 ================
Fri Dec 21 14:04:53 2018 - [info] Starting master failover..
Fri Dec 21 14:04:53 2018 - [info]
From:
10.0.0.247(10.0.0.247:3306) (current master)
+--10.0.0.248(10.0.0.248:3306)
+--10.0.0.249(10.0.0.249:3306)
To:
10.0.0.248(10.0.0.248:3306) (new master)
+--10.0.0.249(10.0.0.249:3306)
Fri Dec 21 14:04:53 2018 - [info]
=============== 省略 ================
Fri Dec 21 14:04:53 2018 - [info] All other slaves should start replication from here. Statement should be: CHANGE MASTER TO MASTER_HOST='10.0.0.248', MASTER_PORT=3306, MASTER_LOG_FILE='mysql-bin.000005', MASTER_LOG_POS=154, MASTER_USER='repl', MASTER_PASSWORD='xxx';
Fri Dec 21 14:04:53 2018 - [info] Executing master IP activate script:
Fri Dec 21 14:04:53 2018 - [info] /etc/masterha/script/master_ip_failover --command=start --ssh_user=mysql --orig_master_host=10.0.0.247 --orig_master_ip=10.0.0.247 --orig_master_port=3306 --new_master_host=10.0.0.248 --new_master_ip=10.0.0.248 --new_master_port=3306 --new_master_user='mha_manager' --new_master_password='mha_manager'
VIP Command: start=sudo /sbin/ifconfig eth0:1 10.0.0.237 netmask 255.255.255.255 stop=sudo /sbin/ifconfig eth0:1 down
Set read_only=0 on the new master.
Enabling the VIP - 10.0.0.237 on the new master - 10.0.0.248
=============== 省略 ================
Fri Dec 21 14:04:55 2018 - [info] 10.0.0.248: Resetting slave info succeeded.
Fri Dec 21 14:04:55 2018 - [info] Master failover to 10.0.0.248(10.0.0.248:3306) completed successfully.
查看新Master VIP
[mysql@cluster02 ~]$ ifconfig
eth0 Link encap:Ethernet HWaddr FA:16:3E:66:7E:E8
inet addr:10.0.0.248 Bcast:10.0.255.255 Mask:255.255.0.0
inet6 addr: fe80::f816:3eff:fe66:7ee8/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:40197173 errors:0 dropped:0 overruns:0 frame:0
TX packets:10470689 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:4063358126 (3.7 GiB) TX bytes:2269241789 (2.1 GiB)
eth0:1 Link encap:Ethernet HWaddr FA:16:3E:66:7E:E8
inet addr:10.0.0.237 Bcast:10.0.0.237 Mask:255.255.255.255
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
可以看到VIP已经成功切换
查看新Master的general日志，可以看到MHA的操作过程, 下面展示部分日志
...
2018-12-21T14:04:41.782336+08:00 5525 Query SHOW SLAVE STATUS
2018-12-21T14:04:41.788318+08:00 5525 Query STOP SLAVE IO_THREAD
2018-12-21T14:04:41.900734+08:00 5525 Query SHOW SLAVE STATUS
2018-12-21T14:04:42.044801+08:00 5525 Query SHOW SLAVE STATUS
2018-12-21T14:04:42.668581+08:00 5525 Query SHOW SLAVE STATUS
2018-12-21T14:04:42.670336+08:00 5525 Query STOP SLAVE SQL_THREAD
...
2018-12-21T14:04:42.863904+08:00 5526 Query SET GLOBAL read_only=0
...
2018-12-21T14:04:43.950986+08:00 5527 Query SET @rpl_semi_sync_slave= 1
...
查看Slave的general日志，可以看到Slave会重新指向
2018-12-21T14:04:04.835218+08:00 90 Query STOP SLAVE IO_THREAD
2018-12-21T14:04:04.955706+08:00 90 Query SHOW SLAVE STATUS
2018-12-21T14:04:05.092123+08:00 90 Query SHOW SLAVE STATUS
2018-12-21T14:04:06.018838+08:00 90 Query SHOW SLAVE STATUS
2018-12-21T14:04:06.034225+08:00 90 Query SHOW SLAVE STATUS
2018-12-21T14:04:06.036613+08:00 90 Query SHOW SLAVE STATUS
2018-12-21T14:04:06.038475+08:00 90 Query STOP SLAVE SQL_THREAD
2018-12-21T14:04:06.160142+08:00 90 Query SHOW SLAVE STATUS
2018-12-21T14:04:06.162224+08:00 90 Query STOP SLAVE
2018-12-21T14:04:06.163171+08:00 90 Query SHOW SLAVE STATUS
2018-12-21T14:04:06.164554+08:00 90 Query RESET SLAVE
2018-12-21T14:04:06.825564+08:00 90 Query CHANGE MASTER TO MASTER_HOST = '10.0.0.248' MASTER_USER = 'repl' MASTER_PASSWORD = <secret> MASTER_PORT = 3306 MASTER_LOG_FILE = 'mysql-bin.000005' MASTER_LOG_POS = 154
2018-12-21T14:04:06.981718+08:00 90 Query SET GLOBAL relay_log_purge=0
2018-12-21T14:04:06.982802+08:00 90 Query START SLAVE
注意: MHA在切换完成后会结束 Manager 进程
4.3 手动切换
切换后Master为Cluster2, 把Cluster1重新指向Cluster2，现在测试一下手动切换，把Master切回Cluster1, 命令如下
masterha_master_switch --conf=/etc/masterha/app2.cnf --master_state=alive --new_master_host=10.0.0.247 --new_master_port=3306 --orig_master_is_new_slave
--orig_master_is_new_slave是将原master切换为新主的slave，默认情况下，是不添加的。
下面是执行过程, 有两个地方要回答 yes/no
[mysql@chengqm ~]$ masterha_master_switch --conf=/etc/masterha/app2.cnf --master_state=alive --new_master_host=10.0.0.247 --new_master_port=3306 --orig_master_is_new_slave
......
It is better to execute FLUSH NO_WRITE_TO_BINLOG TABLES on the master before switching. Is it ok to execute on 10.0.0.248(10.0.0.248:3306)? (YES/no): yes
......
Sun Dec 23 16:50:48 2018 - [info]
From:
10.0.0.248(10.0.0.248:3306) (current master)
+--10.0.0.247(10.0.0.247:3306)
+--10.0.0.249(10.0.0.249:3306)
To:
10.0.0.247(10.0.0.247:3306) (new master)
+--10.0.0.249(10.0.0.249:3306)
+--10.0.0.248(10.0.0.248:3306)
Starting master switch from 10.0.0.248(10.0.0.248:3306) to 10.0.0.247(10.0.0.247:3306)? (yes/NO): yes
......
Sun Dec 23 16:51:36 2018 - [info] 10.0.0.247: Resetting slave info succeeded.
Sun Dec 23 16:51:36 2018 - [info] Switching master to 10.0.0.247(10.0.0.247:3306) completed successfully.
切换成功，查看Cluster1的VIP
[mysql@cluster01 ~]$ ifconfig
eth0 Link encap:Ethernet HWaddr FA:16:3E:DE:80:33
inet addr:10.0.0.247 Bcast:10.0.255.255 Mask:255.255.0.0
inet6 addr: fe80::f816:3eff:fede:8033/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:20585872 errors:0 dropped:0 overruns:0 frame:0
TX packets:5519122 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1785787985 (1.6 GiB) TX bytes:1068115408 (1018.6 MiB)
eth0:1 Link encap:Ethernet HWaddr FA:16:3E:DE:80:33
inet addr:10.0.0.237 Bcast:10.0.0.237 Mask:255.255.255.255
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
注意：手动切换的时候先把 MHA Manager 停了
4.4 停止 MHA
停止 MHA 的命令如下，就不演示了
masterha_stop --conf=配置文件
5 总结
总的来说，MHA是一套非常优秀而且使用比较广的高可用程序，它可以自动补齐日志使得一致性有保证，部署的时候不需要改变原有架构就可以使用。但是使用起来还是有一点复杂的，因为MHA不接管VIP，所以要自己写脚本实现，而且只保证Master高可用，没有Slave高可用，还有就是中继日志要自己设定时任务来清理。
不管怎么说，在没有更好的方案下，MHA还是值得使用的。
附
master_ip_failover 脚本
#!/usr/bin/env perl
use strict;
use warnings FATAL => 'all';
use Getopt::Long;
use MHA::DBHelper;
my (
$command, $ssh_user, $orig_master_host,
$orig_master_ip, $orig_master_port, $new_master_host,
$new_master_ip, $new_master_port, $new_master_user,
$new_master_password
);
my $vip = '10.0.0.237';
my $key = '1';
my $ssh_start_vip = "sudo /sbin/ifconfig eth0:$key $vip netmask 255.255.255.255";
my $ssh_stop_vip = "sudo /sbin/ifconfig eth0:$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,
'new_master_user=s' => \$new_master_user,
'new_master_password=s' => \$new_master_password,
);
exit &main();
sub main {
print "\n\n VIP Command: start=$ssh_start_vip stop=$ssh_stop_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();
# updating global catalog, etc
$exit_code = 0;
};
if ($@) {
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 {
my $new_master_handler = new MHA::DBHelper();
# args: hostname, port, user, password, raise_error_or_not
$new_master_handler->connect( $new_master_ip, $new_master_port,
$new_master_user, $new_master_password, 1 );
## Set read_only=0 on the new master
$new_master_handler->disable_log_bin_local();
print "Set read_only=0 on the new master.\n";
$new_master_handler->disable_read_only();
$new_master_handler->disconnect();
print "Enabling the VIP - $vip on the new master - $new_master_host \n";
&start_vip();
$exit_code = 0;
};
if ($@) {
warn $@;
# If you want to continue failover, exit 10.
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "status" ) {
print "Check script.. OK \n";
# do nothing
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 脚本
#!/usr/bin/env perl
# Copyright (C) 2011 DeNA Co.,Ltd.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
## Note: This is a sample script and is not complete. Modify the script based on your environment.
use strict;
use warnings FATAL => 'all';
use Getopt::Long;
use MHA::DBHelper;
use MHA::NodeUtil;
use Time::HiRes qw( sleep gettimeofday tv_interval );
use Data::Dumper;
my $_tstart;
my $_running_interval = 0.1;
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,
);
my $vip = '10.0.0.237';
my $key = '1';
my $ssh_start_vip = "sudo /sbin/ifconfig eth0:$key $vip netmask 255.255.255.255";
my $ssh_stop_vip = "sudo /sbin/ifconfig eth0:$key down";
exit &main();
sub current_time_us {
my ( $sec, $microsec ) = gettimeofday();
my $curdate = localtime($sec);
return $curdate . " " . sprintf( "%06d", $microsec );
}
sub sleep_until {
my $elapsed = tv_interval($_tstart);
if ( $_running_interval > $elapsed ) {
sleep( $_running_interval - $elapsed );
}
}
sub get_threads_util {
my $dbh = shift;
my $my_connection_id = shift;
my $running_time_threshold = shift;
my $type = shift;
$running_time_threshold = 0 unless ($running_time_threshold);
$type = 0 unless ($type);
my @threads;
my $sth = $dbh->prepare("SHOW PROCESSLIST");
$sth->execute();
while ( my $ref = $sth->fetchrow_hashref() ) {
my $id = $ref->{Id};
my $user = $ref->{User};
my $host = $ref->{Host};
my $command = $ref->{Command};
my $state = $ref->{State};
my $query_time = $ref->{Time};
my $info = $ref->{Info};
$info =~ s/^\s*(.*?)\s*$/$1/ if defined($info);
next if ( $my_connection_id == $id );
next if ( defined($query_time) && $query_time < $running_time_threshold );
next if ( defined($command) && $command eq "Binlog Dump" );
next if ( defined($user) && $user eq "system user" );
next
if ( defined($command)
&& $command eq "Sleep"
&& defined($query_time)
&& $query_time >= 1 );
if ( $type >= 1 ) {
next if ( defined($command) && $command eq "Sleep" );
next if ( defined($command) && $command eq "Connect" );
}
if ( $type >= 2 ) {
next if ( defined($info) && $info =~ m/^select/i );
next if ( defined($info) && $info =~ m/^show/i );
}
push @threads, $ref;
}
return @threads;
}
sub main {
if ( $command eq "stop" ) {
## Gracefully killing connections on the current master
# 1. Set read_only= 1 on the new master
# 2. DROP USER so that no app user can establish new connections
# 3. Set read_only= 1 on the current master
# 4. Kill current queries
# * Any database access failure will result in script die.
my $exit_code = 1;
eval {
## Setting read_only=1 on the new master (to avoid accident)
my $new_master_handler = new MHA::DBHelper();
# args: hostname, port, user, password, raise_error(die_on_error)_or_not
$new_master_handler->connect( $new_master_ip, $new_master_port,
$new_master_user, $new_master_password, 1 );
print current_time_us() . " Set read_only on the new master.. ";
$new_master_handler->enable_read_only();
if ( $new_master_handler->is_read_only() ) {
print "ok.\n";
}
else {
die "Failed!\n";
}
$new_master_handler->disconnect();
# Connecting to the orig master, die if any database error happens
my $orig_master_handler = new MHA::DBHelper();
$orig_master_handler->connect( $orig_master_ip, $orig_master_port,
$orig_master_user, $orig_master_password, 1 );
$orig_master_handler->disable_log_bin_local();
## Waiting for N * 100 milliseconds so that current connections can exit
my $time_until_read_only = 15;
$_tstart = [gettimeofday];
my @threads = get_threads_util( $orig_master_handler->{dbh},
$orig_master_handler->{connection_id} );
while ( $time_until_read_only > 0 && $#threads >= 0 ) {
if ( $time_until_read_only % 5 == 0 ) {
printf
"%s Waiting all running %d threads are disconnected.. (max %d milliseconds)\n",
current_time_us(), $#threads + 1, $time_until_read_only * 100;
if ( $#threads < 5 ) {
print Data::Dumper->new( [$_] )->Indent(0)->Terse(1)->Dump . "\n"
foreach (@threads);
}
}
sleep_until();
$_tstart = [gettimeofday];
$time_until_read_only--;
@threads = get_threads_util( $orig_master_handler->{dbh},
$orig_master_handler->{connection_id} );
}
## Setting read_only=1 on the current master so that nobody(except SUPER) can write
print current_time_us() . " Set read_only=1 on the orig master.. ";
$orig_master_handler->enable_read_only();
if ( $orig_master_handler->is_read_only() ) {
print "ok.\n";
}
else {
die "Failed!\n";
}
## Waiting for M * 100 milliseconds so that current update queries can complete
my $time_until_kill_threads = 5;
@threads = get_threads_util( $orig_master_handler->{dbh},
$orig_master_handler->{connection_id} );
while ( $time_until_kill_threads > 0 && $#threads >= 0 ) {
if ( $time_until_kill_threads % 5 == 0 ) {
printf
"%s Waiting all running %d queries are disconnected.. (max %d milliseconds)\n",
current_time_us(), $#threads + 1, $time_until_kill_threads * 100;
if ( $#threads < 5 ) {
print Data::Dumper->new( [$_] )->Indent(0)->Terse(1)->Dump . "\n"
foreach (@threads);
}
}
sleep_until();
$_tstart = [gettimeofday];
$time_until_kill_threads--;
@threads = get_threads_util( $orig_master_handler->{dbh},
$orig_master_handler->{connection_id} );
}
## Terminating all threads
print current_time_us() . " Killing all application threads..\n";
$orig_master_handler->kill_threads(@threads) if ( $#threads >= 0 );
print current_time_us() . " done.\n";
$orig_master_handler->enable_log_bin_local();
$orig_master_handler->disconnect();
print "Disabling the VIP on old master: $orig_master_host \n";
&stop_vip();
## After finishing the script, MHA executes FLUSH TABLES WITH READ LOCK
$exit_code = 0;
};
if ($@) {
warn "Got Error: $@\n";
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "start" ) {
## Activating master ip on the new master
# 1. Create app user with write privileges
# 2. Moving backup script if needed
# 3. Register new master's ip to the catalog database
# We don't return error even though activating updatable accounts/ip failed so that we don't interrupt slaves' recovery.
# If exit code is 0 or 10, MHA does not abort
my $exit_code = 10;
eval {
my $new_master_handler = new MHA::DBHelper();
# args: hostname, port, user, password, raise_error_or_not
$new_master_handler->connect( $new_master_ip, $new_master_port,
$new_master_user, $new_master_password, 1 );
## Set read_only=0 on the new master
$new_master_handler->disable_log_bin_local();
print current_time_us() . " Set read_only=0 on the new master.\n";
$new_master_handler->disable_read_only();
$new_master_handler->enable_log_bin_local();
$new_master_handler->disconnect();
print "Enabling the VIP - $vip on the new master - $new_master_host \n";
&start_vip();
## Update master ip on the catalog database, etc
$exit_code = 0;
};
if ($@) {
warn "Got Error: $@\n";
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "status" ) {
# do nothing
exit 0;
}
else {
&usage();
exit 1;
}
}
sub start_vip() {
return 0 unless ($new_master_ssh_user);
`ssh $new_master_ssh_user\@$new_master_host \" $ssh_start_vip \"`;
}
sub stop_vip() {
return 0 unless ($orig_master_ssh_user);
`ssh $orig_master_ssh_user\@$orig_master_host \" $ssh_stop_vip \"`;
}
sub usage {
print
"Usage: master_ip_online_change --command=start|stop|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";
die;
}
send_report 脚本
#!/usr/bin/perl
use strict;
use warnings FATAL => 'all';
use Getopt::Long;
#new_master_host and new_slave_hosts are set only when recovering master succeeded
my ( $dead_master_host, $new_master_host, $new_slave_hosts, $subject, $body, $title, $content);
GetOptions(
'orig_master_host=s' => \$dead_master_host,
'new_master_host=s' => \$new_master_host,
'new_slave_hosts=s' => \$new_slave_hosts,
'subject=s' => \$subject,
'body=s' => \$body,
);
# 调用外部脚本
$title="[mha switch]";
$content="`date +'%Y-%m-%d %H:%M'` old_master=".$dead_master_host." new_master=".$new_master_host;
system("sh /etc/masterha/script/send_report.sh $title $content");
exit 0;
清理中继日志定时任务
下面是我的定时任务，参数自行替换, workdir 需要和中继日志在同一个盘
# 每小时清理一次
0 * * * * (/usr/bin/purge_relay_logs --user=mha_manager --password=mha_manager --disable_relay_log_purge --port=3306 --workdir=/tmp/relaylogtmp >> /var/log/purge_relay_logs.log 2>&1)
MHA Wiki: https://github.com/yoshinorim...
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