Multi-Master Replication Manager for MySQL

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2011-04 ( 8)
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Mysql

MySQL DB2 Perl Debian Ubuntu

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Installation Guide
Note: this guide is a draft, feel free to make changes if you see anything that can be improved, expanded on or corrected This installation guide describes a installation of MMM 2 (without the MMM tools) based on Debian Lenny (5.0)

A basic installation contains at least 2 database servers and 1 monitoring server. In this guide, I used 5 servers with Debian Lenny (5.0)

function ip hostname server id

monitoring host 192.168.0.10 mon -

master 1 192.168.0.11 db1 1

master 2 192.168.0.12 db2 2

slave 1 192.168.0.13 db3 3

slave 2 192.168.0.14 db4 4

I used the following virtual IPs. They will be distributed across the hosts by MMM.

ip role description

192.168.0.100 writer Your application should connect to this IP for write queries.

192.168.0.101 reader Your application should connect to one of these four IPs for read queries

192.168.0.102 reader

192.168.0.103 reader

192.168.0.104 reader

Basic configuration of master 1
First we install MySQL on all hosts:

aptitude install mysql-server

Then we edit the configuration file /etc/mysql/my.cnf and add the following lines - be sure to use different server ids for all hosts:

server_id           = 1
log_bin             = /var/log/mysql/mysql-bin.log 
log_bin_index       = /var/log/mysql/mysql-bin.log.index 
relay_log           = /var/log/mysql/mysql-relay-bin 
relay_log_index     = /var/log/mysql/mysql-relay-bin.index 
expire_logs_days    = 10 
max_binlog_size     = 100M 
log_slave_updates   = 1

Then remove the following entry:

bind-address = 127.0.0.1

Do not bind of any specific IP, use 0.0.0.0 instead:

bind-address = 0.0.0.0

Afterwards we need to restart MySQL for our changes to take effect:

/etc/init.d/mysql restart

Create users
Now we can create the required users. We'll need 3 different users:

function description privileges

monitor user used by the mmm monitor to check the health of the MySQL servers REPLICATION CLIENT

agent user used by the mmm agent to change read-only mode, replication master, etc. SUPER, REPLICATION CLIENT, PROCESS

relication user used for replication REPLICATION SLAVE

GRANT REPLICATION CLIENT                 ON *.* TO 'mmm_monitor'@'192.168.0.%' IDENTIFIED BY 'monitor_password';
GRANT SUPER, REPLICATION CLIENT, PROCESS ON *.* TO 'mmm_agent'@'192.168.0.%'   IDENTIFIED BY 'agent_password';
GRANT REPLICATION SLAVE                  ON *.* TO 'replication'@'192.168.0.%' IDENTIFIED BY 'replication_password';

Note: We could be more restrictive here regarding the hosts from which the users are allowed to connect: mmm_monitor is used from 192.168.0.10. mmm_agent and replication are used from 192.168.0.11 - 192.168.0.14.

Synchronisation of data between both databases
I'll assume that db1 contains the correct data. If you have an empty database, you still have to syncronize the accounts we have just created.

First make sure that no one is altering the data while we create a backup.

(db1) mysql> FLUSH TABLES WITH READ LOCK;

Then get the current position in the binary-log. We will need this values when we setup the replication on db2, db3 and db4.

(db1) mysql> SHOW MASTER STATUS;
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+ 
| mysql-bin.000002 |      374 |              |                  | 
+------------------+----------+--------------+------------------+ 
1 row in set (0.00 sec) DON'T CLOSE this mysql-shell. If you close it, the database lock will be removed. Open a second console and type:

db1$ mysqldump -u root -p --all-databases > /tmp/database-backup.sql

Now we can remove the database-lock. Go to the first shell:

(db1) mysql> UNLOCK TABLES;Copy the database backup to db2, db3 and db4. 

db1$ scp /tmp/database-backup.sql <user>@192.168.0.12:/tmp
db1$ scp /tmp/database-backup.sql <user>@192.168.0.13:/tmp
db1$ scp /tmp/database-backup.sql <user>@192.168.0.14:/tmp

Then import this into db2, db3 and db4:

db2$ mysql -u root -p < /tmp/database-backup.sql
db3$ mysql -u root -p < /tmp/database-backup.sql
db4$ mysql -u root -p < /tmp/database-backup.sql

Then flush the privileges on db2, db3 and db4. We have altered the user-table and mysql has to reread this table.

(db2) mysql> FLUSH PRIVILEGES;
(db3) mysql> FLUSH PRIVILEGES;
(db4) mysql> FLUSH PRIVILEGES;

On debian and ubuntu, copy the passwords in /etc/mysql/debian.cnf from db1 to db2, db3 and db4. This password is used for starting and stopping mysql.

Both databases now contain the same data. We now can setup replication to keep it that way.

Note: Import just only add records from dump file. You should drop all databases before import dump file.

Setup replication
Configure replication on db2, db3 and db4 with the following commands:

(db2) mysql> CHANGE MASTER TO master_host='192.168.0.11', master_port=3306, master_user='replication', 
              master_password='replication_password', master_log_file='<file>', master_log_pos=<position>;
(db3) mysql> CHANGE MASTER TO master_host='192.168.0.11', master_port=3306, master_user='replication', 
              master_password='replication_password', master_log_file='<file>', master_log_pos=<position>;
(db4) mysql> CHANGE MASTER TO master_host='192.168.0.11', master_port=3306, master_user='replication', 
              master_password='replication_password',

master_log_file='<file>', master_log_pos=<position>;Please insert the values return by “show master status” on db1 at the <file> and <position> tags.

Start the slave-process on all 3 hosts:

(db2) mysql> START SLAVE;
(db3) mysql> START SLAVE;
(db4) mysql> START SLAVE;

Now check if the replication is running correctly on all hosts:

(db2) mysql> SHOW SLAVE STATUS\G
*************************** 1. row *************************** 
             Slave_IO_State: Waiting for master to send event 
                Master_Host: 192.168.0.11
                Master_User: replication
                Master_Port: 3306 
              Connect_Retry: 60 
…
(db3) mysql> SHOW SLAVE STATUS\G
*************************** 1. row *************************** 
             Slave_IO_State: Waiting for master to send event 
                Master_Host: 192.168.0.11
                Master_User: replication
                Master_Port: 3306 
              Connect_Retry: 60 
…
(db4) mysql> SHOW SLAVE STATUS\G
*************************** 1. row *************************** 
             Slave_IO_State: Waiting for master to send event 
                Master_Host: 192.168.0.11
                Master_User: replication
                Master_Port: 3306 
              Connect_Retry: 60

…
Now we have to make db1 replicate from db2. First we have to determine the values for master_log_file and master_log_pos:

(db2) mysql> SHOW MASTER STATUS;
+------------------+----------+--------------+------------------+ 
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | 
+------------------+----------+--------------+------------------+ 
| mysql-bin.000001 |       98 |              |                  |
+------------------+----------+--------------+------------------+ 
1 row in set (0.00 sec) Now we configure replication on db1 with the following command:

(db1) mysql> CHANGE MASTER TO master_host = '192.168.0.12', master_port=3306, master_user='replication',
              master_password='replication_password', master_log_file='<file>', master_log_pos=<position>;

Now insert the values return by “show master status” on db2 at the <file> and <position> tags.

Start the slave-process:

(db1) mysql> START SLAVE;Now check if the replication is running correctly on db1: 

(db1) mysql> SHOW SLAVE STATUS\G
*************************** 1. row *************************** 
             Slave_IO_State: Waiting for master to send event 
                Master_Host: 192.168.0.12
                Master_User: <replication>
                Master_Port: 3306 
              Connect_Retry: 60

…Replication between the nodes should now be complete. Try it by inserting some data into both db1 and db2 and check that the data will appear on all other nodes.

Install MMM
Create user
Optional: Create user that will be the owner of the MMM scripts and configuration files. This will provide an easier method to securely manage the monitor scripts.

useradd --comment "MMM Script owner" --shell /sbin/nologin

mmmdMonitoring host
First install dependencies:

aptitude install liblog-log4perl-perl libmailtools-perl liblog-dispatch-perl libclass-singleton-perl libproc-daemon-perl libalgorithm-diff-perl libdbi-perl libdbd-mysql-perl

Then fetch the latest mysql-mmm-common*.deb and mysql-mmm-monitor*.deb and install it:

dpkg -i mysql-mmm-common_*.deb mysql-mmm-monitor*.deb

Database hosts
On Ubuntu First install dependencies:

aptitude install liblog-log4perl-perl libmailtools-perl liblog-dispatch-perl iproute libnet-arp-perl libproc-daemon-perl libalgorithm-diff-perl libdbi-perl libdbd-mysql-perl

Then fetch the latest mysql-mmm-common*.deb and mysql-mmm-agent*.deb and install it:

dpkg -i mysql-mmm-common_*.deb mysql-mmm-agent_*.deb

On RedHat

yum install -y mysql-mmm-agent

This will take care of all the dependencies, which may include:

Installed:

mysql-mmm-agent.noarch 0:2.2.1-1.el5

Dependency Installed:

libart_lgpl.x86_64 0:2.3.17-4                                                 
mysql-mmm.noarch 0:2.2.1-1.el5                                                
perl-Algorithm-Diff.noarch 0:1.1902-2.el5                                     
perl-DBD-mysql.x86_64 0:4.008-1.rf                                            
perl-DateManip.noarch 0:5.44-1.2.1                                            
perl-IPC-Shareable.noarch 0:0.60-3.el5                                        
perl-Log-Dispatch.noarch 0:2.20-1.el5                                         
perl-Log-Dispatch-FileRotate.noarch 0:1.16-1.el5                              
perl-Log-Log4perl.noarch 0:1.13-2.el5                                         
perl-MIME-Lite.noarch 0:3.01-5.el5                                            
perl-Mail-Sender.noarch 0:0.8.13-2.el5.1                                      
perl-Mail-Sendmail.noarch 0:0.79-9.el5.1                                      
perl-MailTools.noarch 0:1.77-1.el5                                            
perl-Net-ARP.x86_64 0:1.0.6-2.1.el5                                           
perl-Params-Validate.x86_64 0:0.88-3.el5                                      
perl-Proc-Daemon.noarch 0:0.03-1.el5                                          
perl-TimeDate.noarch 1:1.16-5.el5                                             
perl-XML-DOM.noarch 0:1.44-2.el5                                              
perl-XML-Parser.x86_64 0:2.34-6.1.2.2.1                                       
perl-XML-RegExp.noarch 0:0.03-2.el5                                           
rrdtool.x86_64 0:1.2.27-3.el5                                                 
rrdtool-perl.x86_64 0:1.2.27-3.el5

Configure MMM
All generic configuration-options are grouped in a separate file called /etc/mysql-mmm/mmm_common.conf. This file will be the same on all hosts in the system:

active_master_role          writer


<host default>
    cluster_interface       eth0

    pid_path                /var/run/mmmd_agent.pid
    bin_path                /usr/lib/mysql-mmm/

    replication_user        replication
    replication_password    replication_password

    agent_user              mmm_agent
    agent_password          agent_password
</host>

<host db1>
    ip                      192.168.0.11
    mode                    master
    peer                    db2
</host>

<host db2>
    ip                      192.168.0.12
    mode                    master
    peer                    db1
</host>

<host db3>
    ip                      192.168.0.13
    mode                    slave
</host>

<host db4>
    ip                      192.168.0.14
    mode                    slave
</host>


<role writer>
    hosts                   db1, db2
    ips                     192.168.0.100
    mode                    exclusive
</role>

<role reader>
    hosts                   db1, db2, db3, db4
    ips                     192.168.0.101, 192.168.0.102, 192.168.0.103, 192.168.0.104
    mode                    balanced
</role>

Don't forget to copy this file to all other hosts (including the monitoring host).

On the database hosts we need to edit /etc/mysql-mmm/mmm_agent.conf. Change “db1” accordingly on the other hosts:

include mmm_common.conf
this db1

On the monitor host we need to edit /etc/mysql-mmm/mmm_mon.conf:

include mmm_common.conf

<monitor>
    ip                      127.0.0.1
    pid_path                /var/run/mmmd_mon.pid
    bin_path                /usr/lib/mysql-mmm/
    status_path             /var/lib/misc/mmmd_mon.status
    ping_ips                192.168.0.1, 192.168.0.11, 192.168.0.12, 192.168.0.13, 192.168.0.14
</monitor>

<host default>
    monitor_user            mmm_monitor
    monitor_password        monitor_password
</host>

debug 0

ping_ips are some ips that are pinged to determine whether the network connection of the monitor is ok. I used my switch (192.168.0.1) and the four database server.

Start MMM
Start the agents
(On the database hosts)

Debian/Ubuntu
Edit /etc/default/mysql-mmm-agent to enable the agent:

ENABLED=1Red Hat
RHEL/Fedora does not enable packages to start at boot time per default policy, so you might have to turn it on manually so the agents will start automatically when server is rebooted:

chkconfig mysql-mmm-agent on

Then start it:

/etc/init.d/mysql-mmm-agent start

Start the monitor
(On the monitoring host) Edit /etc/default/mysql-mmm-monitor to enable the monitor:

ENABLED=1

Then start it:

/etc/init.d/mysql-mmm-monitor start

Wait some seconds for mmmd_mon to start up. After a few seconds you can use mmm_control to check the status of the cluster:

mon$ mmm_control show
  db1(192.168.0.11) master/AWAITING_RECOVERY. Roles: 
  db2(192.168.0.12) master/AWAITING_RECOVERY. Roles: 
  db3(192.168.0.13) slave/AWAITING_RECOVERY. Roles: 
  db4(192.168.0.14) slave/AWAITING_RECOVERY. Roles:

Because its the first startup the monitor does not know our hosts, so it sets all hosts to state AWAITING_RECOVERY and logs a warning message:

mon$ tail /var/log/mysql-mmm/mmmd_mon.warn
…
2009/10/28 23:15:28  WARN Detected new host 'db1': Setting its initial state to 'AWAITING_RECOVERY'. Use 'mmm_control set_online db1' to switch it online.
2009/10/28 23:15:28  WARN Detected new host 'db2': Setting its initial state to 'AWAITING_RECOVERY'. Use 'mmm_control set_online db2' to switch it online.
2009/10/28 23:15:28  WARN Detected new host 'db3': Setting its initial state to 'AWAITING_RECOVERY'. Use 'mmm_control set_online db3' to switch it online.

2009/10/28 23:15:28 WARN Detected new host 'db4': Setting its initial state to 'AWAITING_RECOVERY'. Use 'mmm_control set_online db4' to switch it online.Now we set or hosts online (db1 first, because the slaves replicate from this host):

mon$ mmm_control set_online db1
OK: State of 'db1' changed to ONLINE. Now you can wait some time and check its new roles!
mon$ mmm_control set_online db2
OK: State of 'db2' changed to ONLINE. Now you can wait some time and check its new roles!
mon$ mmm_control set_online db3
OK: State of 'db3' changed to ONLINE. Now you can wait some time and check its new roles!
mon$ mmm_control set_online db4
OK: State of 'db4' changed to ONLINE. Now you can wait some time and check its new roles!

原文地址：http://mysql-mmm.org/mmm2:guide

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