[389-users] Replication and High Availalbiltiy

[Rich Megginson]

Bucl, Casper wrote:
>
> Hi,
>
> 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
>
> Configurations.
>
> 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?
>
Yes. Configurations like this have been working at high volume 
installations for several years.

Let's start with - what platform are you running on your systems? What 
version of DS? What procedure did you use to set up and initialize your 
replicas?
>
> Thanks,
>
> Casper
>
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>
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