Re: Differences between MirrorMode and 2-way mulit-master

[Pavlos Parissis <p_pavlos@freemail.gr>]

I am sending this again because somehow never arrived on the list.


On Thu, 18 Sep 2008 21:49:34 +0100 (BST)
ghenry@OpenLDAP.org wrote:

> Please also cc the list.
> 
> > http://www.openldap.org/doc/admin24/replication.html#MirrorMode%20replication
> > 
> > If I understood it correctly, on N-way Multi-Master replication any
> > member can
> > accept write operations while on MirrorMode only must|should accept
> > write
> > operations.
> 
> Correct.
> 
> > I had a MirrorMode configured and I was able to send writes on
> > both servers and each server was replicating the changes without
> > problems.
> > The test which I did was very simple, first add/remove an entry on the
> > first
> > and then add/remove an entry on the second.
> > 
> > So, the above test made to wonder about the differences between
> > MirrorMode and
> > 2-way mulit-master.
> > 
> > what is the reason on a MirrorMode replication to force all write
> > operations to
> > one of the members of the replication?
> 
> Did you read the above link? It doesn't look like you did.

Well I must admit I can't read very so I will guess that
the reason is to guarantee consistency in the database.

How do you guarantee consistency in the database on N-way Multi-Master
replication where any member can accept write operations?
>  
> > BTW, what about the syncpro overlay settings which are not part of
> > the
> > MirrorMode configuration example?
> 
> Again, please read the docs:
> 
> http://www.openldap.org/doc/admin24/replication.html#MirrorMode
> 
> It specifically says:
> 
> "17.4.4.1. Mirror Node Configuration
> 
> This is the same as the Set up the provider slapd section."
> 
> where it links to the section that show the syncprov overlay config.
> 
> Please read the docs.
Oops I must overlooked that.

Thanks,
Pavlos