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 just verified the status on 5 relatively identical setups.
One with 3 MMR masters and 2 read only consumers.
The others with 2 MMR masters and 2 read only consumers.
The contextCSN of the data and cn=config databases were all in sync from what I could
I tried disturbing the peace by runnign some updates and restarting some slaves but could
not immediately product a difference.
This is all openldap-2.4.35 on CentOS or RedHat EL running on a mix of hardware, VMWare
and KVM virtualisiation.
These are all copies of the same setup with different data so the configuration is the
Do you have a checkup script I could deploy against my setups to closely monitor
contextCSN values. Perhaps my manual checks were just too slow.
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