[389-users] Replication and High Availalbiltiy

Bucl, Casper cbucl at firescope.com
Tue Nov 17 04:24:10 UTC 2009

I'm trying to create a high availability ldap for a system I have in place that is currently using multimaster replication. Using a shared storage system isn't an option in this case.

To give you an idea of what our setup looks like,

There are two nodes,  that have replication set up. These are set up as multimasters and have processes that write to both of them. These changes replicate to the other ldap server.
Now I need them to be in a high availability configuration.

I have created duplicates of each node and gotten the high availability portion on each of them to work correctly.

The problem comes with fedora and replication.
I have tried multiple ways of setting up fedora and replication and they always seem to end up with changes not being replicated to the other master when we have failed over to the secondary node. The two most successful one's are below
                Full Mesh: All links were set up as a two way replication.
                                This always ends up with at least 2 nodes showing errors saying it "Can't locate CSN" or "Duplicate node ID"

                                Node1A ------- Node1B
                                     |          \         /       |
                                     |               X            |
                                     |          /         \       |
                                Node2A ------- Node2B

                Single replication agreement between VIPs
                                In this configuration, we initially copied over the slapd instance directory on setup of the second HA node (Node1A to Node1B) so that the settings and configurations are identical on both. Then as changes were made to the ldap, we created backups using db2bak. These backups are copied over to the failover box and then imported on startup of fedora ds. This doesn't appear to backup the changelog and ends up with an error saying "Can't locate CSN" again.

                                Node1 VIP
                                Node2 VIP

I have tried other things as well and they were a lot less fruitful than the two examples I have here.

Has anyone set up a high availability scenario similar to this? Can anyone suggest a different process or configuration that would accomplish what I'm after?

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