Hi all!
I am currently trying to chase some problems in an n-way multi-master setup with three servers. We have used the instructions at
http://www.openldap.org/doc/admin24/replication.html#N-Way%20Multi-Master
as our guidance and we are using OpenLDAP version 2.4.11.
The result we see currently is that replication works only partially, with some strange errors here and there.
As I believe it will be pointless to post all our cn=config LDIF here and explain scenarios which work and those which don't, I thought it would be more productive to double-check that I have correctly understand what I *should* be seeing happen on my systems and how I can properly monitor this. My problem may be that I still need to learn how to properly monitor my slapd.
To begin with, I would just ask for confirmation of my proper understanding of the documentation:
1. A master server is a server which is using the syncprov overlay (servers/slapd/overlays/syncprov.c). This overlay will do little more than just provide a synchronization cookie (CSN) which consumers may ask for to find out what needs to get replicated and what not.
2. A consumer server is a server in which an additional thread is running which will query the master(s) in a given interval to ask for updated and if any, get them over the wire and into the local copy of the database. This synchronization thread is servers/slapd/syncrepl.c I guess?
3. An N-Way Multi-Master setup is a setup in which N servers are each a master and any of the others is a consumer of all other masters?
I am I right up to here?
So what I fail to understand is:
1. What is the difference between Mirror Mode and N-Way Multi-Master? Especially given that in N-Way Multi-Master, have to set olcMirrorMode to TRUE.
2. Given that I have added a 'Sync' value to the olcLogLevel attribute, what would be the "health check" information I should be watching in the log for to see that replication is attempted as expected.
3. What problems should I be watching for in the logs?
4. Could I for example manually ask a master (using some ldapsearch statement, pretending I was the consumer) what the master thinks which entries I would have to update?
Regards, Torsten