Re: [389-users] Replication and High Availalbiltiy

-----Original Message----- From: fedora-directory-users-bounces(a)redhat.com [mailto:fedora-directory-users-bounces@redhat.com] On Behalf Of Rich Megginson Sent: Tuesday, November 17, 2009 12:35 PM To: General discussion list for the 389 Directory server project. Subject: Re: [389-users] Replication and High Availalbiltiy Bucl, Casper wrote: > -----Original Message----- > From: fedora-directory-users-bounces(a)redhat.com > [mailto:fedora-directory-users-bounces@redhat.com] On Behalf Of Rich > Megginson > Sent: Tuesday, November 17, 2009 8:23 AM > To: General discussion list for the 389 Directory server project. > Subject: Re: [389-users] Replication and High Availalbiltiy > > 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 >> >> --------------------------------------------------------------------- >> - >> -- >> >> -- >> 389 users mailing list >> 389-users(a)redhat.com >> https://www.redhat.com/mailman/listinfo/fedora-directory-users >> >> >> > The environment is set up using Fedora-Directory 1.0.4 > > What platform? I would suggest using the latest (1.2.2 or 1.2.4 which is in testing). We have fixed many, many bugs in replication since 1.0.4, and the issue with the CSN you are reporting sounds like a bug that has been fixed in 1.2.x. > To set up the multimaster replication I used the mmr.pl script. When reinitializing the consumers, I use ldapmodify and set the nsDS5BeginReplicaRefresh to start. > > Another question about the fully meshed configuration, Can there be more nodes? We will be wanting to add another HA node to the environment so this would take the total to 6 directory servers. The idea being that there is a central hub that is kind of the global master. Everyone replicates their info up to it and then it gets redistributed back out to the others. > > Yes, you can have more than 4 masters. > Would the easier method be to copy the changelog information over to the standby node? > No. > Is there a method to do this? > > Not really. > Thanks, > Casper > > > -- > 389 users mailing list > 389-users(a)redhat.com > https://www.redhat.com/mailman/listinfo/fedora-directory-users > > Hi Rich, What is the proper way to reinitialize the replication agreement in a multimaster configuration. Whenever I try using the nsDS5BeginReplicaRefresh method, it ends up creating a new changelog on the node being refreshed and then it begins having replication issues. Notably the "Can't locate CSN" error. Could this be something related to some of the bugs you were speaking of?

Casper -- 389 users mailing list 389-users(a)redhat.com https://www.redhat.com/mailman/listinfo/fedora-directory-users