使用MMM搭建Mysql同步高可用

come from：http://blog.chinaunix.net/u/25264/showart_1811549.html

使用MMM搭建Mysql同步高可用性

先介紹下MMM
MMM是 mysql-master-master的縮寫。
MMM專案來自 Google：

MySQL本身沒有提供replication failover的解決方案，那麼如何使Replication方案具有HA的功能呢，那就是MMM。
大家都知道mysql的同步機制在解決實際問題上具有很高的可行性，特別對讀寫負載比較高的web2.0來說，那麼在實際應用中必須保證mysql的穩定性及效能。

Master-Master Replication
1、使用兩個MySQL資料庫db1,db2，互為Master和Slave，即：
一邊db1作為db2的master，一旦有資料寫向db0時，db2定時從db1更新
另一邊db2也作為db1的master，一旦有資料寫向db2時，db1也定時從db2獲得更新

2、但從AppServer的角度來說，同時只有一個結點db1扮演Master，另外一個結點db2扮演Slave，不能同時兩個結點扮演Master。即AppSever總是把write操作分配某個資料庫(db1)，除非db1 failed，被切換。

3、如果扮演Slave的資料庫結點db2 Failed了：
a)此時appServer要能夠把所有的read,write分配給db1，read操作不再指向db2
b)一旦db2恢復過來後，繼續充當Slave角色，並告訴AppServer可以將read分配給它了

4、如果扮演Master的資料庫結點db1 Failed了
a)此時appServer要能夠把所有的寫操作從db1切換分配給db2，也就是切換Master由db2充當
b)db1恢復過來後，充當Slave的角色，Master由db2繼續扮演


MMM利用了虛擬IP的技術：1個網路卡可以同時使用多個IP。
(所以使用MMM時，需要2*n+1個IP，n為mysql資料庫結點個數，包括master,slave)

MMM有3個重要的器件:
1、mmmd_mon    -     資料庫控制節點執行。
2、mmm_control -  資料庫控制節點執行。
3、mmmd_agent  -     資料庫節點（master/slave）執行。


本文環境：
server1 ip: 192.168.1.225 ; virtual read ip:192.168.1.229
server2 ip: 192.168.1.226 ; virtual read ip:192.168.1.230

server3 ip: 192.168.1.227
virtual write ip: 192.168.1.231


配置過程很簡單，
server1 server2 replication雙向 master-master
server1 server2 安裝mmm並配置mmm_agent.conf
server3 安裝mmm並配置mmm_mon.conf

1，首先我們要先配置好master-master雙向同步，這一步就不多說了。
2，安裝部署MMM
3臺伺服器都要安裝MMM軟體，安裝過程如下：

安裝如下perl模組，為MMM安裝做好準備，
cpan Algorithm::Diff
cpan Proc::Daemon
cpan Time::HiRes
cpan DBI
cpan DBD::mysql

wget
tar xzf mmm-1.0-pre2.tar.bz2
cd mmm-1.0-pre2
./install.pl

3，在server1上配置MMM
修改配置 /usr/local/mmm/etc/mmm_agent.conf，如下：

#
# Master-Master Manager config (agent)
#

# Debug mode
debug no

# Paths
pid_path /usr/local/mmm/var/mmmd_agent.pid
bin_path /usr/local/mmm/bin

# Logging setup
log mydebug
file /usr/local/mmm/var/mmm-debug.log
level debug

log mytraps
file /usr/local/mmm/var/mmm-traps.log
level trap

# MMMD command socket tcp-port and ip
bind_port 9989

# Cluster interface
cluster_interface eth0

# Define current server id
this db1
mode master

# For masters
peer db2

# Cluster hosts addresses and access params
host db1
ip 192.168.1.225
port 3306
user rep_agent
password RepAgent

host db2
ip 192.168.1.226
port 3306
user rep_agent
password RepAgent

GRANT ALL PRIVILEGES on *.* to 'rep_agent'@'%′ identified by 'RepAgent';
GRANT ALL PRIVILEGES on *.* to 'rep_monitor'@'%' identified by 'RepMonitor';


3，在server2上配置MMM
修改配置 /usr/local/mmm/etc/mmm_agent.conf，如下：

#
# Master-Master Manager config (agent)
#

# Debug mode
debug no

# Paths
pid_path /usr/local/mmm/var/mmmd_agent.pid
bin_path /usr/local/mmm/bin

# Logging setup
log mydebug
file /usr/local/mmm/var/mmm-debug.log
level debug

log mytraps
file /usr/local/mmm/var/mmm-traps.log
level trap

# MMMD command socket tcp-port and ip
bind_port 9989

# Cluster interface
cluster_interface eth0

# Define current server id
this db2
mode master

# For masters
peer db1

# Cluster hosts addresses and access params
host db1
ip 192.168.1.225
port 3306
user rep_agent
password RepAgent

host db2
ip 192.168.1.226
port 3306
user rep_agent
password RepAgent

GRANT ALL PRIVILEGES on *.* to 'rep_agent'@'%′ identified by 'RepAgent';
GRANT ALL PRIVILEGES on *.* to 'rep_monitor'@'%' identified by 'RepMonitor';


3，在server3上配置MMM
修改配置 /usr/local/mmm/etc/mmm_mon.conf，如下：

#
# Master-Master Manager config (monitor)
#

# Debug mode
debug no

# Paths
pid_path /usr/local/mmm/var/mmmd.pid
status_path /usr/local/mmm/var/mmmd.status
bin_path /usr/local/mmm/bin

# Logging setup
log mydebug
    file /usr/local/mmm/var/mmm-debug.log
    level debug

log mytraps
    file /usr/local/mmm/var/mmm-traps.log
    level trap
    email root@localhost


# MMMD command socket tcp-port
bind_port 9988
agent_port 9989
monitor_ip 127.0.0.1

# Cluster interface
cluster_interface eth0

# Cluster hosts addresses and access params
host db1
    ip 192.168.1.225
    port 3306
    user rep_monitor
    password RepMonitor
    mode master
    peer db2

host db2
    ip 192.168.1.226
    port 3306
    user rep_monitor
    password RepMonitor
    mode master
    peer db1



#
# Define roles
#

active_master_role writer

# Mysql Reader role
role reader
    mode balanced
    servers db1, db2
    ip 192.168.1.229, 192.168.1.230

# Mysql Writer role
role writer
    mode exclusive
    servers db1, db2
    ip 192.168.1.231

#
# Checks parameters
#

# Ping checker
check ping
    check_period 1
    trap_period 5
    timeout 2

# Mysql checker
# (restarts after 10000 checks to prevent memory leaks)
check mysql
    check_period 1
    trap_period  2
    timeout 2
    restart_after 10000

# Mysql replication backlog checker
# (restarts after 10000 checks to prevent memory leaks)
check rep_backlog
    check_period 5
    trap_period 10
    max_backlog 60
    timeout 2
    restart_after 10000

# Mysql replication threads checker
# (restarts after 10000 checks to prevent memory leaks)
check rep_threads
    check_period 1
    trap_period 5
    timeout 2
    restart_after 10000
    
   
啟動
server1 與 server2上分別啟動mmmd_agent
[root@localhost ~]# mmmd_agent
[root@localhost ~]# netstat -tlnp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State       PID/Program name  
tcp        0      0 0.0.0.0:9989                0.0.0.0:*                   LISTEN      26010/perl 

出現9989埠說明啟動成功。


server3上啟動mmmd_mon
[root@localhost etc]# mmmd_mon
Reading config file: 'mmm_mon.conf'
$VAR1 = {
          'db2' => {
                     'roles' => [
                                  'reader(192.168.1.229;)'
                                ],
                     'version' => '0',
                     'state' => 'ONLINE'
                   },
          'db1' => {
                     'roles' => [
                                  'reader(192.168.1.230;)',
                                  'writer(192.168.1.231;)'
                                ],
                     'version' => '0',
                     'state' => 'ONLINE'
                   }
        };
Role: 'reader(192.168.1.229;)'
Adding role: 'reader' with ip '192.168.1.229'
Role: 'reader(192.168.1.230;)'
Adding role: 'reader' with ip '192.168.1.230'
Role: 'writer(192.168.1.231;)'
Adding role: 'writer' with ip '192.168.1.231'

在管理節點上（server3）啟動db節點：
mmm_control set_online db1
mmm_control set_online db2

檢視下節點狀態：
[root@localhost etc]# mmm_control show
Config file: mmm_mon.conf
Daemon is running!
Servers status:
  db1(192.168.1.225): master/ONLINE. Roles: reader(192.168.1.230;), writer(192.168.1.231;)
  db2(192.168.1.226): master/ONLINE. Roles: reader(192.168.1.229;)



OK,能看到這個效果說明你已經配置成功了，下面就可以隨心所欲的折騰mysql的異常狀態，來進行測試。