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Re: Initializing cn=config from existing multi-master setup via syncrepl - "new entry is older than ours"

--On Tuesday, February 03, 2009 6:32 PM +0100 Jonathan Clarke <jclarke@linagora.com> wrote:

Hi all,

We have setup a couple of servers in N-way multimaster config, using
back-config, as explained in the admin guide. These all use RE24,
checked out today.

We are now trying to add another server to the existing cluster. To do
this, we want to replicate the existing cn=config branch from the
cluster, to initialize the config for the new server.

To do this, we start the new server with a minimal cn=config branch,
making it a syncrepl consumer to an existing server (consumer only, no
multimaster on this new server):

How do you expect to replicate the cn=config branch from a multi-master and end up with only a replica? I'm lost. Once it finishes, it'll be a multi-master, not a pure replica.

If you already have a syncrepl replica, and are just wanting to set up a new one, you should slapcat the config tree from the existing replica and slapadd it to the new one before starting it. This will avoid all these problems. Otherwise, you need to come up with a new cn=config tree that is *not* replicated from one of the masters, which again avoids the issues you are seeing.

I.e., for new serves, either slapcat the config tree from one that matches the template you are creating and slapadd that to the new server, or come up with an entirely new config tree.

If you really want to have fun, set up another database on the master to store the cn=config tree for replicas under a different branch, and then use slapo-rwm to rewrite it as a config tree for any replica that connects to it. This should work in theory, although I've never done it.



Quanah Gibson-Mount
Principal Software Engineer
Zimbra, Inc
Zimbra ::  the leader in open source messaging and collaboration