Re: contextCSN values and MMR

Quanah Gibson-Mount wrote: > On Aug 10, 2013, at 12:01 PM, Quanah Gibson-Mount <quanah(a)zimbra.com&gt; wrote: >> On Aug 10, 2013, at 11:08 AM, Michael Ströder <michael(a)stroeder.com&gt; 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). >> >> I always set the syncprov checkpoint on all servers, replicas or masters. > > Correction. I load slapo-syncprov on all replicated db backends. I don't set the checkpoint. As said this is a MMR setup => slapo-syncprov is loaded on all replicated DB backends Anythings else why contextCSN is not updated? Ciao, Michael.