Subject: Single-Master Failover Recovery and Automated Replication

From: "Hugo Tavares" <[email-masked]>
Date: Mon, 14 Oct 2002 13:13:34 +0100

Greetings

I'm doing some search before implementing the LDAP services and I've noticed
that there is a big question in synchronizing the information after recovery
from a master fail in a single-master environment. As it's written in
section 5.2 of "General Usage Profile for LDAPv3 Replication":

"If the broken master is returned to service as a slave,
 then the administrator must, external to LDUP, distribute and resolve
 whatever pending changes remained undistributed and unresolved from the
 time immediately before it was removed from service. If the broken
 master is returned as a new master, then care must be taken with its
 replacement master to ensure that all of its pending changes are
 distributed and resolved before it is returned to duty as a slave."

For a failover recovery I will use the heartbeat protocol with linux-HA or
the LVS software (I still don't know what to use), and this protocol seems
to deal fine the services, since
when the masters goes down the heartbeat puts the slave being the master for
providing updates to the clients, but, when the master comes up the
heartbeat puts everything like the original configuration, although the
problem of synchronization stills.

My questions are:
	Is there any protocol wich leads with this? (I don't think so)
	Do you have any perspectives for implementing an autometed system to lead
with this?

Thank you

Hugo Tavares