RE: Documentation volunteer (was: Cluster replication: multiple masters)

["Howard Chu" <hyc@highlandsun.com>]

When you can solve the problems in
 http://www.openldap.org/lists/openldap-software/200206/msg00446.html
then you might have something worth writing about.

In the general case, there are unsolvable problems with conflict resolution.

There is a specific case where you might profitably use multimastering: in a
situation where you have multiple redundant servers, but only a single one is
ever targeted for write operations (thus avoiding change conflicts). In this
scenario, if the "write server" crashes you can immediately failover to any
one of the other redundant servers; in essence you are still doing
master-slave replication, but with automatic promotion of a slave to master
status. It is not straightforward to enforce the single-writer usage though;
i.e., there's no simple way to ensure that clients only write to the
currently selected write server.

  -- Howard Chu
  Chief Architect, Symas Corp.       Director, Highland Sun
  http://www.symas.com               http://highlandsun.com/hyc
  Symas: Premier OpenSource Development and Support

> -----Original Message-----
> From: owner-openldap-software@OpenLDAP.org
> [mailto:owner-openldap-software@OpenLDAP.org]On Behalf Of Derek Simkowiak

> 	So (with some help, no less) I managed to find the web-browsable
> list archives, cleverly hidden under the heading of "List
> Archives" on the
> lists web page.
>
> 	Searching for "multiple masters" gives a bunch of very old
> messages (95% more than a year old, many over two years old)
> mostly about
> some "experimental" code in the 2.0.8 CVS tree.
>
> 	My first question is, "huh?".  Why would multi-master
> replication
> require any code whatsoever?  It seems like you'd just
> configure slurpd as
> per my last message in this thread.  If someone familiar with this
> 'experimental' code could comment, I would be very grateful.
>
> 	The second question is, what is the current status?  Is anybody
> using this?  And again, why would this be anything more than
> having slurpd
> feed the log to multiple replicas in both directions?
>
> 	I would be happy to write an up-to-date mini-HOWTO on my
> experience, so if anyone knows anything about this (or has examples of
> where it's deployed), please reply.
>
>
> Thank You,
> Derek Simkowiak
>
>
>
>