The messages you see could be transient messages, and if replication is working than this seems to be the case. If not we would need more data to investigate: deployment info, relicaIDs of all servers, ruvs, logs,.....

Here is some background info: there are some scenarios where a csn could not be found in the changelog, eg if updates were aplied on the supplier during a total init, they could be part of the data and database ruv, but not in the changelog of the initialized replica. ds did try to use an alternative csn in cases where it could not be found, but this had the risk of missing updates, so we decided to change it and make this misssing csn a non fatal error, backoff and retry, if another supplier would have updated the replica in between, the starting csn could have changed and be found. so if the reported missing csns change and replication continues everything is ok, although I think the messages should stop at some point.


There is a configuration parameter for a replciation agreement to trigger the previous behaviour of picking an alternative csn:

nsds5ReplicaIgnoreMissingChange

with potential values "once", "always".

where "once" just tries to kickstart replication by using another csn and "always" changes the default behaviour


On 05/11/2017 06:53 PM, Goran Marik wrote:
Hi,

After an upgrade to Centos 7.3.1611 with “yum update", we started seeing the 
following messages in the logs:
“””
May  9 21:58:28 inf01 ns-slapd[4323]: [09/May/2017:21:58:28.519724479 +0000] 
NSMMReplicationPlugin - changelog program - 
agmt="cn=cloneAgreement1-inf02.dev.ecobee.com-pki-tomcat" (inf02:389): CSN 
576b34e8000a050f0000 not found, we aren't as up to date, or we purged
May  9 21:58:28 inf01 ns-slapd[4323]: [09/May/2017:21:58:28.550459233 +0000] 
NSMMReplicationPlugin - 
agmt="cn=cloneAgreement1-inf02.dev.ecobee.com-pki-tomcat" (inf02:389): Data 
required to update replica has been purged from the changelog. The replica must be 
reinitialized.
May  9 21:58:32 inf01 ns-slapd[4323]: [09/May/2017:21:58:32.588245476 +0000] 
agmt="cn=cloneAgreement1-inf02.dev.ecobee.com-pki-tomcat" (inf02:389) - Can't 
locate CSN 576b34e8000a050f0000 in the changelog (DB rc=-30988). If replication stops, 
the consumer may need to be reinitialized.
May  9 21:58:32 inf01 ns-slapd[4323]: [09/May/2017:21:58:32.611400689 +0000] 
NSMMReplicationPlugin - changelog program - 
agmt="cn=cloneAgreement1-inf02.dev.ecobee.com-pki-tomcat" (inf02:389): CSN 
576b34e8000a050f0000 not found, we aren't as up to date, or we purged
May  9 21:58:32 inf01 ns-slapd[4323]: [09/May/2017:21:58:32.642226385 +0000] 
NSMMReplicationPlugin - 
agmt="cn=cloneAgreement1-inf02.dev.ecobee.com-pki-tomcat" (inf02:389): Data 
required to update replica has been purged from the changelog. The replica must be 
reinitialized.
“””

The log messages are pretty frequently, every few seconds, and report few 
different CSN numbers that cannot be located.

This happens only on one replica out of 4. We’ve tried "ipa-replica-manage 
re-initialize —from” and “ipa-csreplica-manage re-initialize —from” several times, 
but while both commands report success, the log messages continue to happen. The 
server was rebooted and “systemctl restart ipa” was done few times as well.

The replica seems to be working fine despite the errors, but I’m worried that 
the logs indicate underlaying problem we are not fully detecting. I would like 
to understand better what is triggering this behaviour and how to fix it, and 
if someone else saw them after a recent upgrades.

The software versions are 389-ds-base-1.3.5.10-20.el7_3.x86_64 and 
ipa-server-4.4.0-14.el7.centos.7.x86_64

Thanks,
Goran

--
Goran Marik
Senior Systems Developer

ecobee
250 University Ave, Suite 400
Toronto, ON M5H 3E5




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