On Aug 10, 2013, at 12:01 PM, Quanah Gibson-Mount <[email protected]> wrote:
> > > On Aug 10, 2013, at 11:08 AM, Michael Ströder <[email protected]> wrote: > >> Christian Kratzer wrote: >>> On Sat, 10 Aug 2013, Michael Ströder 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 >> though... >> >> => will try to play with this (I don't need a high write rate on those >> systems). >> >> Ciao, Michael. > > I always set the syncprov checkpoint on all servers, replicas or masters. > > --Quanah Correction. I load slapo-syncprov on all replicated db backends. I don't set the checkpoint.
