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Re: contextCSN values and MMR


On Sat, 10 Aug 2013, Michael StrÃder wrote:


Are contextCSN values on all replicas really in sync if changes were correctly

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.

Not sure though.


Ciao, Michael.

Christian Kratzer                      CK Software GmbH
Email:   ck@cksoft.de                  Wildberger Weg 24/2
Phone:   +49 7032 893 997 - 0          D-71126 Gaeufelden
Fax:     +49 7032 893 997 - 9          HRB 245288, Amtsgericht Stuttgart
Web:     http://www.cksoft.de/         Geschaeftsfuehrer: Christian Kratzer