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Re: contextCSN values and MMR

Christian Kratzer wrote:
> On Sat, 10 Aug 2013, Michael StrÃder wrote:
>> Are contextCSN values on all replicas really in sync if changes were correctly
>> replicated?
>> I've implemented a monitoring check used with normal MMR setup (OpenLDAP
>> 2.4.35, own build on Debian Squeeze) which also checks the contextCSN values
>> on all replicas compared by server-id.
>> Sometimes we observe, even in isolated tests, that contextCSN values for a
>> certain server-id differ for quite a while (up to hours) even though the
>> changes coming from that server were definitely replicated to all other
>> replicas. After a while the contextCSN values get suddenly updated.
>> Unfortunately this does not always happen.
>> Any hint is highly appreciated.
> I have always suspected that this is due to the specific setting of:
>        syncprov-checkpoint <ops> <minutes>
>               After a write operation has succeeded, write the contextCSN to
> the underlying database  if  <ops>  write
>               operations  or more than <minutes> time have passed since the
> last checkpoint. Checkpointing is disabled
>               by default.

Thanks for following-up.

AFAICS the above directive specifys when to write the contextCSN to the DB on
disk similar to checkpoint directives for DB backends. So in case of a server
crashing you have a quite recent contextCSN with the server-id of this
particular server.

But since all replicas are up and running and I query the contextCSN values
via LDAP I presume this is not relevant for my problem. Well, one never knows

=> will try to play with this (I don't need a high write rate on those systems).

Ciao, Michael.

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