Re: Complex multi-master topology

[Quanah Gibson-Mount <quanah@zimbra.com>]

--On Thursday, October 01, 2015 12:26 PM -0400 Patrick 
<pbrideau@kronostechnologies.com> wrote:

> I've been trying to create a complex multi-master replication of
> cn=config for a week now...  I'm using the core debian package: slapd
> 2.4.40+dfsg-1+deb8u1
>
>
> I've seen someone claiming it could work but cannot find configs related
> to this kind of topology.
> http://www.slideshare.net/ghenry/openldap-replication-strategies
> (slide #24)
>
>
> When building a simple multimaster (two or three nodes) everything works
> as planned.  But in the case some nodes cannot talk to others, i cannot
> find a way to make it works.
>
>
> Let's take this example
>
> +-------+       +-------+       +-------+
> | ldap1 | <---> | ldap2 | <---> | ldap3 |
> +-------+       +-------+       +-------+
>
> and say:
> olcSyncRepl: rid=001
>              searchbase="cn=config"
>              type=refreshAndPersist
>              provider=ldap://ldap1
> olcSyncRepl: rid=002
>              searchbase="cn=config"
>              type=refreshAndPersist
>              provider=ldap://ldap2
> olcSyncRepl: rid=003
>              searchbase="cn=config"
>              type=refreshAndPersist
>              provider=ldap://ldap3
>
> Where initialy:
>    ldap1 have rid=002
>    ldap2 have rid=001 and rid=003
>    ldap3 have rid=002
>
>
> Soon everyone get rid=001 rid=002 rid=003 and ldap3 cannot talk to ldap1
> and it does not work...
>
> And even if i don't care about the connexion between ldap1 and ldap3
> failing, the replication does not work either... if ldap1 change
> something, it gets replicated to ldap2 but not ldap3.
>
>
> Also, i've been trying to use exattrs=Syncrepl but if someone change his
> Syncrepl, it get deleted on the other node...  Someone seems to have
> seen this with memberof overlay ?
>
> http://www.openldap.org/lists/openldap-technical/201505/msg00124.html
>
>
>
> Anyone have references to help me get to my goal?

While I avoid replicating cn=config, we have several customers with 3+ MMR 
setups for their back-mdb databases that work just fine.  You fail to note 
what your *serverID* is set to on each master, as that's required to be 
different.

I would suggest you set your log level to "sync stats" and determine why 
the various masters are unable to talk to one another.

--Quanah


--

Quanah Gibson-Mount
Platform Architect
Zimbra, Inc.
--------------------
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