Re: Troubleshooting synchronization

Hi Torsten,

"Torsten Schlabach (Tascel eG)" <[email protected]> writes:

> 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?

Yes.
> 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?

Well, without delta-syncrepl all data of a modified entry is
synchronised. Delta-syncrepl requires a special log database while the
consumer requests information on the modified entries and only
requests the modified attributes. 
>
> 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?

Yes

> - 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?

Mirror Mode is just synchronisation between two or more providers,
while only one provider is active (see mirrormode on/off parameter)
and the others are in stand-by mode, consumers only connect to the
active provider. 
N-Way Multimaster is a network of active providers which synchronise
data by means of syncrepl. In other words, a client may write to any
of this providers and it is up to the providers to stay synchronised.
Multimaster is not covered by the protocol.

-Dieter

-- 
Dieter Klünter | Systemberatung
http://dkluenter.de
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