MySQL的高可用(MHA)

時間 2019-11-18

標籤 mysql 可用 mha 欄目 MySQL 简体版

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MySQL的高可用(MHA)

MHA簡介

MHA:Master High Availability,對主節點進行監控，可實現自動故障轉移至其餘從節點；經過提高某一從節點爲新的主節點，基於主從複製實現，還須要客戶端配合實現，目前MHA主要支持一主二從，即一臺充當master，一臺充當備用master，另一臺充當從數據庫，出於機器成本的考慮，淘寶進行了改造，目前淘寶TMHA已經一主一從。node

MHA架構

MHA的工做原理

MHA是由一臺manager服務器遠程監控主服務器,當主服務器掛了提高一臺從服務器做爲主服務器。
當主節點掛了，manager首先要查看哪臺從節點，同步的數據最多，而後提高同步最多的從節點爲主節點，再將其他的MySQL服務器對他作從節點。
若是原主節點沒完全死透，manager會讓新的主機經過ssh協議遠程鏈接到原先的主節點，拉取二進制日誌進行同步。若是主節死透了那就放棄。　　mysql

MHA搭建

環境準備

1、準備4臺主機，管理節點1臺，主節點MySQL服務器1臺，從節點MySQL服務器2臺

主機	IP
Manager	192.168.73.111
Master	192.168.73.110
Slave1	192.168.73.112
Slave2	192.168.73.113

wget https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
rpm -ivh epel-release-latest-7.noarch.rpm

2、將Manager管理節點配置爲時間服務器，向全部MySQL服務器提供時間同步。

1.安裝chrony服務sql

[root@Manager ~]# yum install -y chrony

2.修改chrony配置文件數據庫

[root@Manager ~]# vim /etc/chrony.conf 
server 172.22.0.1 iburst
allow 192.168.0.0/16
local stratum 10

3.啓動chrony服務vim

[root@Manager ~]# systemctl start chronyd

4.將MySQL服務器與Manager服務器進行時間同步
4.1在全部MySQL主機上修改配置文件並啓動，並啓動服務centos

[root@Master ~]# sed -i '/^server 0/i server 192.168.73.111 iburst' /etc/chrony.conf
[root@Master ~]# systemctl start chronyd

4.2確認時間同步服務器

[root@Master ~]# chronyc sources -v
210 Number of sources = 1

  .-- Source mode  '^' = server, '=' = peer, '#' = local clock.
 / .- Source state '*' = current synced, '+' = combined , '-' = not combined,
| /   '?' = unreachable, 'x' = time may be in error, '~' = time too variable.
||                                                 .- xxxx [ yyyy ] +/- zzzz
||      Reachability register (octal) -.           |  xxxx = adjusted offset,
||      Log2(Polling interval) --.      |          |  yyyy = measured offset,
||                                \     |          |  zzzz = estimated error.
||                                 |    |           \
MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
^* 192.168.73.111                4   6   377    54    +25us[  +41us] +/-  105ms

3、配置ssh爲的密鑰認證登錄

當主節點宕機，manager會讓從節點經過ssh協議去嘗試鏈接主節點，並拉取二進制日誌，因此要時用密鑰的認證方式讓從節點登錄到主節點拉取數據。
1.在manager服務器上生成私鑰文件架構

[root@Manager ~]# ssh-keygen 
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:yAvC2PJUlRyAf1udlrVXzmIsUljTdUdW6X6FVpQ3Ajo root@Manager
The key's randomart image is:
+---[RSA 2048]----+
|   ..ooo   ++. +%|
|  .  .o   o oo.=*|
|   ..    E = oo*o|
| + ...... B o B.+|
|o = ..ooS. . =...|
| + . ...       ..|
|  .   .         .|
|                 |
|                 |
+----[SHA256]-----+

2.將公鑰文件複製給本身app

[root@Manager ~]# ssh-copy-id 127.0.0.1

3.將整個~/.ssh目錄複製給全部的MySQL主機dom

[root@Manager ~]# scp -r ~/.ssh 192.168.73.110:/root

至此全部環境準備完畢

1、配置主從複製

主節點配置

1.修改配置文件

[root@Master ~]# vim /etc/my.cnf
[mysqld]
server-id=1
log-bin
binlog-format=row
skip_name_resolve

2.啓動數據庫服務

[root@Master ~]# systemctl start mariadb

3.建立主從複製帳號

[root@Master ~]# mysql -e "GRANT REPLICATION SLAVE ON *.* TO 'repluser'@'192.168.73.%' IDENTIFIED BY 'centos';"

4.添加mha的管理帳號，讓管理節點遠程鏈接到主機用來設置主從調整

[root@Master ~]# mysql -e "GRANT ALL ON *.* TO 'mhauser'@'192.168.73.%' IDENTIFIED BY 'centos';"

從節點配置

1.修改配置文件

[root@Slave1 ~]# vim /etc/my.cnf
[mysqld]
server-id=2
read-only
log-bin
relay_log_purge=0
skip_name_resolve

2.啓動服務

[root@Slave1 ~]# systemctl start mariadb

3.配置CHANGE MASTER TO

MariaDB [(none)]> CHANGE MASTER TO MASTER_HOST='192.168.73.110', MASTER_USER='repluser',MASTER_PASSWORD='centos',MASTER_PORT=3306,MASTER_LOG_FILE='mariadb-bin.000001',MASTER_LOG_POS=245;
Query OK, 0 rows affected (0.00 sec)

4.啓動線程

MariaDB [(none)]> START SLAVE;
Query OK, 0 rows affected (0.00 sec)

在Slave2節點上也執行相同的操做，此處步驟省略，須要注意server-id須要修改成和其餘主從節點不一樣

5.測試
主節點導入hellodb庫

[root@Master ~]# mysql < hellodb_innodb.sql

從節點查看是否同步
slave1

[root@Slave1 ~]# mysql -e "SHOW DATABASES;"
+--------------------+
| Database           |
+--------------------+
| information_schema |
| hellodb            |
| mysql              |
| performance_schema |
| test               |
+--------------------+

Slave2

[root@Slave2 ~]# mysql -e "SHOW DATABASES;"
+--------------------+
| Database           |
+--------------------+
| information_schema |
| hellodb            |
| mysql              |
| performance_schema |
| test               |
+--------------------+

2、配置管理節點及被管理節點

1.在管理節上安裝mha4mysql-manager、mha4mysql-node，將兩個包放在同一目錄下

[root@Manager ~]# yum install *.rpm -y  #這兩個包有依賴管理須要一塊兒安裝

2.在全部被管理節點上安裝mha4mysql-node

[root@Master ~]# yum install mha4mysql-node-0.56-0.el6.noarch.rpm -y

[root@Slave1 ~]# yum install mha4mysql-node-0.56-0.el6.noarch.rpm -y

[root@Slave2 ~]# yum install mha4mysql-node-0.56-0.el6.noarch.rpm -y

3.在管理節點上建立配置文件

[root@Manager ~]# vim /etc/mha/aap1.conf

[server default] 
user=mhauser 
password=centos
manager_workdir=/data/mastermha/app1/ 
manager_log=/data/mastermha/app1/manager.log 
remote_workdir=/data/mastermha/app1/ 
ssh_user=root 
repl_user=repluser 
repl_password=centos
ping_interval=1

[server1] 
hostname=192.168.73.110
candidate_master=1 
[server2] 
hostname=192.168.73.112
candidate_master=1 
[server3]
hostname=192.168.73.113
candidate_master=1

4.作檢查
4.1檢查ssh鏈接

[root@Manager ~]# masterha_check_ssh --conf=/etc/mha/aap1.conf

4.2檢查主從複製

[root@Manager ~]# masterha_check_repl --conf=/etc/mha/aap1.conf

5.以上兩項所有成功後啓動程序
mha這個程序是跑在前臺的，一次性的可使用nohub或screen來解決跑在前臺的問題

[root@Manager ~]# masterha_manager --conf=/etc/mha/aap1.conf

3、測試

1.在master上跑個存儲過程，導入存儲過程

[root@Master ~]# mysql hellodb < testlog.sql

2.調用存儲過程

MariaDB [(none)]> USE hellodb
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
MariaDB [hellodb]> call pro_testlog;

3.另起一個主節點窗口將主節點斷網

[root@Master ~]# ifdown ens33

4.manager端完成切換退出，查看日誌，查看新的主節點是哪臺slave

[root@Manager app1]# tail /data/mastermha/app1/manager.log

Started automated(non-interactive) failover.
The latest slave 192.168.73.112(192.168.73.112:3306) has all relay logs for recovery.
Selected 192.168.73.112(192.168.73.112:3306) as a new master.
192.168.73.112(192.168.73.112:3306): OK: Applying all logs succeeded.
192.168.73.113(192.168.73.113:3306): This host has the latest relay log events.
Generating relay diff files from the latest slave succeeded.
192.168.73.113(192.168.73.113:3306): OK: Applying all logs succeeded. Slave started, replicating from 192.168.73.112(192.168.73.112:3306)
192.168.73.112(192.168.73.112:3306): Resetting slave info succeeded.
Master failover to 192.168.73.112(192.168.73.112:3306) completed successfully.
#此處顯示最新的主節點爲192.168.73.112

因爲從節點在配置文件中定義的爲read-only，此時被提高爲主能執行寫操做時應爲管理服務器上有管理帳號，他將從節點的服務器全局變量read_only給關閉了

[root@Slave1 ~]# mysql -e "SELECT @@read_only;"
+-------------+
| @@read_only |
+-------------+
|           0 |
+-------------+

爲了防止服務服務重啓再次變爲read-only，此時須要對新主節點的配置文件進行修改將read-only行註釋

[mysqld]
server-id=2
#read-only
log-bin
relay_log_purge=0
skip_name_resolve

4、測試新的主節點

1.對hellodb.teachers表插入數據

[root@Slave1 ~]# mysql -e "INSERT hellodb.teachers VALUES(5,'Tang San',30,'M');"

2.Slave2主機上查看是否同步

[root@Slave2 ~]# mysql -e "SELECT * FROM hellodb.teachers;"
+-----+---------------+-----+--------+
| TID | Name          | Age | Gender |
+-----+---------------+-----+--------+
|   1 | Song Jiang    |  45 | M      |
|   2 | Zhang Sanfeng |  94 | M      |
|   3 | Miejue Shitai |  77 | F      |
|   4 | Lin Chaoying  |  93 | F      |
|   5 | Tang San      |  30 | M      |    #已經同步
+-----+---------------+-----+--------+