Shantanu's Blog

MMM (Master-Master Replication Manager) is a set of flexible scripts to perform monitoring/failover and management of MySQL Master-Master replication configurations (with only one node writable at any time). The toolset also has the ability to read balance standard master/slave configurations with any number of slaves, so you can use it to move virtual IP addresses around a group of servers depending on whether they are behind in replication.

The main functionality is provided through the following three scripts:

mmm_mond: monitoring daemon which does all monitoring work and makes all decisions about roles moving and so on.
mmm_agentd: agent daemon which runs on each MySQL server and provides monitoring node with simple set of remote services.
mmm_control: simple script dedicated to management of the mmm_mond processes by commands.


# start and stop MMM Monitor
/etc/init.d/mysql-mmm-monitor start
/etc/init.d/mysql-mmm-monitor status
/etc/init.d/mysql-mmm-monitor stop

# Show MMM details
/usr/sbin/mmm_control show
/usr/sbin/mmm_control show | grep -v 'ONLINE'
/usr/sbin/useradd --comment "MMM Script owner" --shell /sbin/nologin mmmd

# Config files
vi /etc/default/mysql-mmm-monitor
vi /etc/mysql-mmm/mmm_common.conf
vi /etc/mysql-mmm/mmm_mon.conf

A typical MMM setup looks like this...
/usr/sbin/mmm_control show
db1(192.168.100.101) master/ONLINE. Roles: reader(192.168.100.122)
db2(192.168.100.102) master/ONLINE. Roles: reader(192.168.100.121), writer(192.168.100.123)

And in order to check the logs on monitor and DB servers you can use the command...
tail /var/log/mysql-mmm/mmm_mond.log
tail /var/log/mysql-mmm/mmm_agentd.log

Here are the permissions those need to be created in order to monitor the replication.

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

GRANT REPLICATION SLAVE ON *.* TO 'replication'@'%' IDENTIFIED BY 'replication_password';

grant replication slave on *.* to 'slave_user'@'%' IDENTIFIED BY 'slave_user';
# One of the last 2 statements can be used

And do not forget to check if the following setting is there in my.cnf file
log_slave_updates = 1

More info can be found here...
http://mysql-mmm.org/mmm2:guide

Labels: mysql FAQ