add slave to existing master-master replication

[Teri LeBlanc]

Hello - we have an existing circular replication setup like this:

M1 <---> M2

settings are as follows:

M1:

server-id=1
auto_increment_increment=2
auto_increment_offset=1
log-slave-updates
sync_binlog=1

M2:

server-id=2
auto_increment_increment=2
auto_increment_offset=2
log-slave-updates
sync_binlog=1

We are adding 2 servers in a second datacenter as a DR solution. Not sure yet which config we are going with, but it will be one of these 3:

M1 <---> M2
|
|
V
S1 ----> S2

or

M2 <---> M1
|
|
V
S1 ----> S2

or

M1 <---> M2 ------> S2
|
|
|
V
S1

I am unclear on how to set auto_increment_increment and auto_increment_offset on the new slaves. It doesn't matter while they are slaves, but it could matter if they ever have to get promoted to masters. I am thinking that these values on the slaves should match whatever master they are connected to, so in the event of disaster they kind of "take over" for that master.

I'd appreciate any comments on this

Teri



Edited 2 time(s). Last edit at 03/28/2012 03:38PM by Teri LeBlanc.