Hi Dieter! Your answers are very helpful, thanks for that!
>>> directory design, I wonder if I am suffering from a misconception here, >>> i.e. mixing up N-way multi-master and mirror mode possibly. >> >> probably So looking at http://www.openldap.org/doc/admin24/replication.html#Configuring%20the%20different%20replication%20types What I understand is: 18.3.1. Syncrepl This is about the syncrepl engine as such. So this is applicable to all types of replication and it's the technical basics, right? 18.3.2. Delta-syncrepl I guess this is simple master-slave, isn't it? Though I fail to understand why this is about deltas while obviously the other mechanisms aren't, are they? 18.3.3. N-Way Multi-Master This was the first section which explained something which sounded like what I am looking for. So I went for it. 18.3.4. MirrorMode Looking at the config example, I just can't tell the difference to 18.3.3. N-Way Multi-Master except: - samples in this section are not cn=config based, but I guess that shouldn't matter but it's just a question of which mechanism I like to use, isn't it? - in both N-Way Multi-Master and in Mirror Mode I have serverID, mirrormode on and syncrepl statements. So what actually is the difference between Mirror Mode and N-Way Multi-Master except having 2 servers or three servers? Regards, Torsten Dieter Kluenter schrieb: > Hi Torsten! > > "Torsten Schlabach (Tascel eG)" <[email protected]> writes: > >> Hi Dieter! >> >>> The answer is quite simple: do not use multimaster replication in a >>> production environment. In most cases the requirement for multimaster >>> replication is just based on poor directory design. >> If this is a "do not use feature", for what reason has it been included >> in the software, in the first place. > > Well, there is the protocol RFC 4510 and the OpenLDAP Project is > aiming to be the reference implementation of this protocol, on the > other hand is the OpenLDAP Project a community driven project: > http://www.openldap.org/project > that is, features not being part of the protocol but may be of > interest to the community, can be included. > With regard to multimaster replication, this feature has only been > included since 2.3 (if I remember correctly) and has undergone heavy > recoding ever since. I personally consider multimaster replication > still as beta and not stable for production use. > >>> Slapd in a synchronized environment is, with a few exceptions which >>> have only been fixed recently, rock stable, I know of environments >>> with up to 150 consumers. >> When you say "synchronized", do you mean one master and n slaves? > > Yes >> When you say, the requirement for N-way multi-master is usually poor >> directory design, I wonder if I am suffering from a misconception here, >> i.e. mixing up N-way multi-master and mirror mode possibly. > > probably >> What we want to achieve is a HA solution where *all* directory data is >> stored on more than one physical machine. I know I can do that by having >> a master and a slave. But then I would need to have a mechanism entirely >> external to slapd that if the master fails I turn the slave into a >> master and vice versa. (However this could be reliably achieved.) > > What you describe is Mirror Mode. > >> So the idea for N-way multi-master was just: I can point the DNS entry >> to whatever server in my cluster (possibly there may be more than two) >> and it will be a writeable directory and I won't ever loose any >> information I write into that LDAP cloud. > > OK, this requirement does not include multimaster replication, but > only Mirror Mode of a HA cluster of providers and chaining write > operations of consumers to the active provider. > > -Dieter >
