Re: Does EM support Master-Master replicaiton?
Posted by: Mark Leith
Date: May 11, 2012 03:01AM

Yes it does, it is usually denoted as "Circular" in the replication tab.

We actually support two different modes of topology discovery..

Mode 1:

From the agent, we try to read the "" file from the data directory of the slave, gather the connection details for the master, and connect to the master, to try and read the uuid of the master instance from the "mysql.inventory" table. This is reported back to the MEM server as the "Master_UUID" data item.

As long as we have an agent on the master as well, then both agents will also report back the uuid from each mysql.inventory table as the instance identifier. We then use all of these UUID values to construct the topology.

This is the most foolproof mode, but it requires that the replication user has access to the mysql.inventory table on it's master (in circular replication, this is a requirement on all servers in the ring), and it requires that the agent is started as the same user as MySQL is (typically the "MySQL" user), so that we can read the file from the data directory.

Mode 2:

If the above fails (no access at the FS or master mysql.inventory table), then we fall back to IP address and port number matching. Each agent gets all the IP addresses of each NI on each machine, and sends that back to MEM, as well as the ports that each instance is listening on. We get the "Master_Host" from SHOW SLAVE STATUS (if it's a FQDN, we try to do an IP lookup, otherwise just use the IP if provided) and "Master_Port", and we use that to do the topology walking, matching on known IP:Port patterns.

This doesn't require any special access like mode 1, however it does solve issues around things like virtual IP addresses, which are often used between replication systems..

I would first try and ensure that we have a shot at "Mode 1" - make sure your agent is started with the right user, and that the replication user is granted SELECT on the mysql.inventory table.

If you have any further problems with this - please open a support issue, and we can look at your debug logs to find out what is going wrong.



Best regards,


Mark Leith
Senior Software Development Manager
MySQL Enterprise Tools @ Oracle

Options: ReplyQuote

Written By
Re: Does EM support Master-Master replicaiton?
May 11, 2012 03:01AM

Sorry, you can't reply to this topic. It has been closed.

Content reproduced on this site is the property of the respective copyright holders. It is not reviewed in advance by Oracle and does not necessarily represent the opinion of Oracle or any other party.