RE: explain diff between multimaster and mirror mode

["Jorge Medina" <jmedina@e-dialog.com>]

I am no expert and English is not my mother tongue either, but here is
what I understand:

In a multi-master configuration, the system may not be able to reconcile
the databases if a partition has occurred and multiple writes/delete
occurred.

      "If a network is partitioned and multiple clients start writing to
each of the "masters" 
      then reconciliation will be a pain; it may be best to simply deny
writes to the clients 
      that are partitioned from the single master"
      
In MirrorMode, you still have two masters replicating to each other, but
you use a third component -the load balancer- to redirect all requests
to only one of the masters. If this master fails, then it switches to
the other server. Seems to me that the masters are aware of this
configuration because of the directive "mirrormode on"

In the proposed Failover Configuration, all requests are first sent to a
cluster of slaves. Those slaves process all read requests and redirect
the write requests to a "cluster" of masters; but in fact the load
balancer is sending all write requests to a single master unless it
fails, in which case it sends the request to the second master.

-Jorge

________________________________________
From: openldap-software-bounces+jmedina=e-dialog.com@OpenLDAP.org
[mailto:openldap-software-bounces+jmedina=e-dialog.com@OpenLDAP.org] On
Behalf Of Liutauras Adomaitis
Sent: Friday, July 18, 2008 2:22 AM
To: openldap-software@openldap.org
Subject: explain diff between multimaster and mirror mode

Since English is not my mother tong, can someone explain me what is ment
in 
http://www.openldap.org/doc/admin24/replication.html#Mixture%20of%20both
%20Pull%20and%20Push%20based
by saying "MirrorMode is not what is termed as a Multi-Master solution.
This is because writes have to go to one of the mirror nodes at a time"?
Is it that I have always write to the same master? Can I do writes some
times to one sometimes to another, but not to both at the same time?
Which way Multi-Mater or Mirror-Mode is easier to recover from broken
replication. On Master-Slave I just delete Slave db and restart ldap,
this is acceptible for me because there is no much data to replicate.

I'm using Master-Slave replication now, but it seems that it is not good
for some reason, which I don't know and can't explain. So trying to find
an alternative, but don't want to learn on my own mistakes on production
:)

Liutauras