Master-master replication example

Detailed description of this example configuration could be found in “Typical use-cases of mmm-deployment” document.

Let’s take a looks on example configuration files for such configuration. Every deployment of mmm requires N+1 installation where N is number of MySQL servers and 1 is monitoring server (can be combined with application server). Following examples would be named as mmm_mon.conf for minitoring server and mmm_agent.conf for database servers.

mmm_mon.conf is following:

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#
# Master-Master Manager config (monitor)
#

# Debug mode
debug no

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

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

log mytraps
file /opt/mmm/var/mmm-traps.log
level trap

# 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 master1
ip 192.168.1.8
port 3306
user rep_monitor
password RepMonitor
mode master
peer master2

host master2
ip 192.168.1.9
port 3306
user rep_monitor
password RepMonitor
mode master
peer master1

#
# Define roles
#

active_master_role writer

# Mysql Reader role
role reader
mode balanced
servers master1, master2
ip 192.168.1.100, 192.168.1.101

# Mysql Writer role
role writer
mode exclusive
servers master1, master2
ip 192.168.1.200, 192.168.1.201

#
# Checks parameters
#

# Ping checker
check ping
check_period 1
trap_period 5
timeout 2

# Mysql checker
check mysql
check_period 1
trap_period 2
timeout 2

# Mysql replication backlog checker
check rep_backlog
check_period 5
trap_period 10
max_backlog 60
timeout 2

# Mysql replication threads checker
check rep_threads
check_period 1
trap_period 5
timeout 2

In this config file I want to highlight few sections:

Cluster hosts addresses and access params – this section describe IPs and credentials that will be used in all monitoring checks. So, it is required to have active MySQL instances listening on these IPs and appropriate access restrictions set to allow monitoring server to MySQL instance.
Define roles – this section defines what roles we have in our cluster and what IPs will be used for each role.

All other config sections are pretty standard and described in details in configuration files section of mmm guide.