Friday, November 13, 2009

Installing MEM agent on a cluster on the logical host

The goal is to have only one entry in the Enterprise Monitor Dashboard that shows the status of the MySQL instance, no matter on which physical server in runs. There are two ways to achieve this:
  • You can install the agent on both physical nodes
  • You can install the agent on a shared storage.
In either case you have to make sure, that only one agent runs at a time. You have to integrate the agent into your cluster framework. I will not describe how this works, as it is highly dependant on your cluster framework.

The following description assumes, that you will install the agent on both physical nodes.

  1. Install the agent but DO NOT START the agent yet.

  2. Edit the [agent-installdir]/etc/mysql-monitor-agent.ini
    In the [mysql-proxy] section add the following line:
    agent-host-id=[logical hostname]
  3. Do steps 1. and 2. for the other cluster node as well.

  4. Include the agent in the cluster's failover group so that it will start automatically on that node, where the MySQL instance is running.

  5. Start the agent via the cluster framework.

  6. The entry in MEM will get the hostname of the first node that runs MySQL. Even after a failover this name will stay. You should change that name to the virtual hostname of the virtual ip adress of your MySQL service. Use the MEM BUI, choose the tab "Settings". From the secondary menu right below the tabs choose "Manage Servers". If you move the mouse over the server name a submenu will appear. Choose "Rename" and enter the name of the virtual IP.

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