On Mon, 12 Aug 2013, Michael Ströder wrote:
Christian Kratzer wrote:
> On Mon, 12 Aug 2013, Ulrich Windl wrote:
>>> 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
>>> last checkpoint. Checkpointing is disabled
>>> by default.
>>> Not sure though.
>> do you "query" by slapcat or by an LDAP search? For the former it's
>> that contextCSN is updated lazily. For the latter I'm not sure.
> I have had the same use case Michael is getting at in the back of me
> head for some time. I would also like to verify replication status by
> checking the contextCSN on all servers via an ldapsearch from a
> monitoring script.
> I would expect an ldapsearch of the contextCSN to deliver a current
> and valid value that should be identical over all servers.
> It seems this is not the case. I will run a couple of tests to verify
> this myself in my testbed of 2 mmr masters and 2 slaves.
Even worse my results with 3 MMR providers and 2 read-only consumer replicas
are sometimes not very pleasant regarding data consistency. At the moment this
test servers are running as VMs on ESX server. I will repeat my tests with
real hardware to make sure there's nothing wrong because of the virtual
I have a mixed hardware / virtualisation based environment available. Will check the
contextCSN over there and let you know.
Using delta-sync MMR does not make sense in my case because entries
completely added, modified or delete. (I have no influence on the client app
same here. I also like the added bonus of giving the customer a stable and easy recovery
- stop slapd
- rm -f /var/lib/ldap/*
- start slapd
The customer has a relatively small dataset so replication is a matter seconds or at least
under a couple of minutes.
Christian Kratzer CK Software GmbH
Email: ck(a)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
Geschaeftsfuehrer: Christian Kratzer