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From:Walter Heck - Date:March 12 2010 11:31pm
Subject:Re: move from master-slave to master-master
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Possibly a bit offtopic, but are you sure you want to go to
Master-Master replication? It's quite tricky and has a pretty high
chance of ending you up in complicated and hard-to-recover-from
situations. If it is High Availability (HA) you are after, I recommend
you have a look at MMM ( We have a whole bunch
of clients running it and it makes things a whole lot easier.

As for full-on Master-Master replication: You need to make the slave
master of your current master, in such a way that both machines are
each other's slave and each other's master. To do that, setting up
auto_increment_increment and auto_increment_offset, log-slave-updates
should be enough. Then you just setup master-slave replication between
your current slave and your current master and you should be good to

Good luck!

Walter Heck

Engineer @ Open Query
htttp:// | |

On Sat, Mar 13, 2010 at 01:39, Database System <database100@stripped> wrote:
> Hi,
> I have master-slave replication running. Now I need to modify it to a master-master
> replication. I knew how to setup master -master from scrach. It has a set
> auto_increment_offset=1 (or 2 for second master)
> but since existing replication is running, if I simply put this line in ini (beside
> set auto_increment_increment and do change master to ...), then restart the servers, will
> server know where to start the offset?
> Thanks,
> Lisa
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move from master-slave to master-masterDatabase System12 Mar
  • Re: move from master-slave to master-masterWalter Heck - OlinData.com13 Mar