Multi-Master LDAP

[Philipp Klaus <ldapml@internet.access.ch>]

Hi,

I recently set up LDAP-Servers for quite a large site and had to problem
to create a configuration which should have to be fail tolerant.
OPENLDAP has the ability to replicate from a master to multiple slave
servers but when the master stops working no write command is possible.
Our site had to be save for such situations so a fail-over server must
be able to accept write commands and distribute it to the other servers
still working.
After a short look at the manual and the code I realized that this
wouldn't work without patching the code. The patch I made is available
at the address below, perhaps it will be included in future versions. I
made all changes using ifdefs so anyone who don't want the multi master
ability switch it off.
The change has one drawback: replication over more than one level isn't
possible now because I use the Replicator-DN to decide which write
commands to add to the replication log file.

The patched slapd works for 3 weeks in a production environment without
any problem arising from the change.

multi master patch:
http://www.internet.access.ch/openldap/openldap-1.2.1-MultiMaster.patch

Philipp Klaus