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Re: A couple of questions regarding replication and user mapping

On 9/21/18 10:45 AM, Dieter Klünter wrote:
> Am Thu, 20 Sep 2018 22:29:11 +0200
> schrieb Karsten Heymann <karsten.heymann@gmail.com>:
>> 4. What happens when a lot of concurrent writes happen to two masters
>> configured in mirror mode? We had a loadbalancer misconfiguration and
>> the loadbalancers were using simple round robin to write to the
>> masters. Can this result in diverging content on the two masters?
> 
> First write should win, depending on timestamp

@Dieter: Did you mean last write should win?

In theory OpenLDAP does conflict resolution based on the "timestamp" in
the entryCSN attribute value. This also means that you need really tight
time synchronization.

In general if you have really *many* concurrent writes going to several
MMR replicas you will likely run into trouble. I'd recommend to avoid that.

Another problem with naive load-balancing is that most applications do
read-after-write operations within very short time span which will fail
because of replication latency.

Ciao, Michael.

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