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Re: N-way multimaster error code 53 - shadow context

On 19.02.2009 12:00, Adrien Futschik wrote:
I am still testing n-way multi master replication with OpenLDAP 2.4.14. I
don't know why I could modify my olcSyncrepl attribute from my data bdb.

I am binding with cn=config, and I can modify the olcSyncrepl attribute
from olcDatabase={0}config, but not from olcDatabase={1}bdb !

I am getting this error :
08:57:25: Failed to update entry olcDatabase={1}bdb, cn=config
Reason: [LDAP: error code 53 - shadow context; no update referral]

This appends on both masters. Is this supposed to be like that ? I have
configured cn=config to replicate, this should work right ?
When you configure a database with syncrepl replication, it is marked as
a shadow context. This makes sense for the general case when a database
is a "slave" of a master server. Trying to update a shadowed database
will return the "shadow context; no update referral" error, unless a
"updateref" is set on that DB.

However, if you're using multi-master, and have set mirrormode on, this
should no longer be the case, and all updates will be accepted.

So you should check:
1) That mirrormode is on
2) That your slapd listeners match your syncrepl providers, as I
suggested in another thread

If this is all the case, please give us your configuration, and tell us
what operations you do that lead to this situation.


I have been doing some more tests : I have removed all olcSyncrepl attributes from olcDatabase={1}bdb and recreated them and here is what netstat showed me :

Whether I am trying to update on M1 or M2 doesn't matter. The only way I could
get things back to normal, was to restart M1&  M2 (not sure restarting M2 was

I think you may be hitting the bug described in ITS #5954 (http://www.openldap.org/its/?findid=5954). When deleting one of several syncrepl directives via cn=config, the wrong one may be deleted for the running instance in 2.4.14. This problem has been corrected in RE24, available by cvs.

In any case, if you are encountering this problem, it can be solved by restarting slapd. This is of course a pain, so I suggest you try RE24.

Jonathan Clarke
LinID - Open Source Identity Management
27 rue de Berri, 75008 Paris
Tel: 01 58 18 68 28 / 06 99 60 03 10
Ldap Synchronization Connector (LSC) - http://lsc-project.org/