14.3 Replication


MySQL Enterprise Monitor is available as part of the MySQL Enterprise subscription, learn more at http://www.mysql.com/products/.

Navigate to the Replication page by choosing Replication under Dashboards. This page summarizes the state of your replication servers; you can drill down to see details about any master or slave. Using this page helps you avoid running the SHOW SLAVE STATUS command over and over on multiple servers; for consistency, the Replication page uses some of the same keywords as the output from that command.


Set up agents to monitor each master and slave server. Only servers that are monitored appear on this page.

The Replication page groups all master servers with their slaves. Masters and their slaves are autodiscovered and a grouping is created, based on the way that the servers are interconnected (known as the replication topology). Scans run on a five minute interval, so depending upon the order of discovery, it can take as long as 2 polling intervals to create a complete group.

Discovery events are logged to the Replication log. To view this log, navigate to the Settings page and choose the Logs link. View all replication-related events by clicking the Replication link. This log can be a useful tool for debugging the replication topology discovery process.


Auto-discovery with remote monitoring only functions with MySQL 5.6 and later. Earlier versions of MySQL server require the Agent to be installed on the same host as the monitored MySQL instance. This is because mysqld did not expose the master's uuid value via SHOW SLAVE STATUS until version 5.6.

You can manage replication groups from the MySQL Instances page in the same way as other groups. However, any slaves removed from a server group are automatically restored to that group. You can also add non-slaves to a replication grouping.


The replication group name can also be edited from the Replication dashboard by clicking the drop-down menu for the group, and choosing Rename Group.

Replication Page Details

Choose a value from the Refresh drop-down list box to set the rate at which information is updated. This refresh rate applies only to the information presented on this page: It is independent of the rate set for the Monitor tab.

The following columns describe replication master and slave servers:

Most column headings are active links; click the header to change the display order. Sorting works differently for different column groupings. Click the Time Behind header to order servers by the number of seconds they are behind their master. The server topology is respected regardless of sort order. For example, in a TREE topology, ordering occurs within branches only.

If the Agent is down, instances show in bold red in the Servers column. The Slave IO and the Slave SQL columns display stopped in red text if these threads are not running. If an agent is down, the last know status of the IO or SQL threads is shown in italics.

Clicking a master server opens a dialog box that displays information about the server. The information shown includes:

The dialog box also includes a link to hide or show the slave servers.

Clicking a slave server opens a dialog window showing extensive information about the slave.

Deleted Replication Groups

This section describes the how replication groups are treated if the replication topology changes.

  • If all instances which make up a replication group are deleted, the replication group is deleted automatically.

    If a replication group is automatically deleted, an event is generated and a message is displayed in the MySQL Enterprise Monitor User Interface.

  • If the deleted replication group was associated with an event handler, the replication group is automatically removed from the event handler's definition.

    An event is generated and a message is displayed in the MySQL Enterprise Monitor User Interface stating that the group was removed.

  • If the deleted replication group was the only filter defined on the event handler, the event handler is suspended.

    An event is generated and a message is displayed in the MySQL Enterprise Monitor User Interface stating that the group was removed and the event handler suspended.

Usage Notes

For information on the kinds of problems you might find while monitoring replication, and how to solve them, see Troubleshooting Replication and Improving Replication Performance.