Re: (ITS#8490) changes not written to accesslog, causing replicas to loop syncing

[quanah@zimbra.com]

--On Thursday, September 01, 2016 7:52 AM +0000 quanah@openldap.org wrote:

> Full_Name: Quanah Gibson-Mount
> Version: OpenLDAP 2.4.44
> OS: Linux 2.6
> URL: ftp://ftp.openldap.org/incoming/
> Submission from: (NULL) (75.111.52.177)
>
>
> In a 2-node MMR setup.  Node 1 is getting a lot of write traffic.  Both
> node 1 and node 2 have 3 replicas each.  At some point, a change is
> received by node 1, which writes the change to its accesslog DB and its
> primary DB.  It's 3 replicas are all correctly updated.  MMR node 2
> receives the change, updates its primary DB, but *fails* to write the
> change to the accesslog DB.  However, it *does* write the CSN update to
> the accesslog DB successfully.  This causes all of its replicas to also
> update their CSN.  Then a change comes in triggering a constraint
> violation on the replicas, but fully accepted by their master.

So the above summary is incorrect.  While 3 replicas did go out of sync... 
2 belonged to the primary master (node1), and 1 belonged to the secondary 
master (node 2).  So really, 4 systems didn't log the change (MMR node 2, 
ldap05, ldap07, ldap09).

So I have no explanation at the moment why ldap06, ldap08, and ldap10 were 
not affected.

--Quanah


--

Quanah Gibson-Mount