On Thu, Mar 04, 2021 at 01:09:55PM +0100, Michael Ströder wrote:
> On 3/4/21 12:20 PM, Ondřej Kuzník wrote:
>> If it takes 1 second to replicate a change and a previous change
>> happened x seconds before this one there's going to be a window of 1
>> second where you see an x second CSN difference between the provider and
>> consumer. In no way does it mean the consumer is x seconds behind.
> 
> I'm talking about the contextCSN difference being visible for several
> *hours* while the changes have been already successfully replicated.
> Replication delay is very short, syncrepl type is refreshAndPersist.

Don't think I've ever seen this outside slapcat (only checkpoints affect
the on-disk version). Please submit a bug if you can replicate this.

>> If there's an acceptable delay of n seconds, you better wait for that
>> amount of time before raising an alarm,
> 
> And what's an appropriate value for n? 86400? ;-]

Depends where in the galaxy you place your replicas :)

>> See the logic in syncmonitor[0]
> 
> Ideally I'd like to query cn=monitor whether slapd thinks replication is
> in a healthy state.

Consumer will never think its replication is slow/broken (unless it gets
an actual error and you can already see that in cn=monitor). Provider
might want to expose some information but that's not implemented yet and
will not be able to spot many issues if other providers exist.

-- 
Ondřej Kuzník
Senior Software Engineer
Symas Corporation                       http://www.symas.com
Packaged, certified, and supported LDAP solutions powered by OpenLDAP

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