--On Friday, February 08, 2013 5:56 PM -0500 John Madden
<[email protected]> wrote:
There is no configuration difference at this point. I think there was
one initially ages ago. The only difference between MMR and mirror-mode
MMR is that in the latter case, writes only go to a single master
instead of any master in the cluster.
"Writes only go to one master in the cluster." What happens if they
don't? If I DNS round-robin a pair of systems and MirrorMode them, what
happens?
Then they aren't mirror mode, and any persistent client is going to be
writing to whatever master it first connected to. DNS round-robin will
never guarantee you are in mirror mode.
In other words, if N-Way supports two masters writing while MM does not,
how can it not have a different configuration?
It has nothing to do with configuration of MMR, which I think is the point
you're missing. It has purely to do with configuring it so only one master
ever takes writes at a given time. With writes only ever going to one
master, you have a 100% guarantee you'll never get a conflict between two
masters. Which you essentially get with delta-syncrepl MMR anyway.
I seem to remember MirrorMode being very easy to set up yet N-Way taking
significantly more time but looking back at the docs I think that's just
a matter of the syncrepl setups taking a bit of effort.
Correct. A replica can only talk to a single "master". If you set up
mirror mode, then the replica can purely talk to the load-balance name, and
never have an issue if one of the masters in the cluster goes down.
--Quanah
--
Quanah Gibson-Mount
Sr. Member of Technical Staff
Zimbra, Inc
A Division of VMware, Inc.
--------------------
Zimbra :: the leader in open source messaging and collaboration
