Gordon Messmer wrote: > Chris St. Pierre wrote: > >> You'll want to set up two-way replication agreements between each pair >> of hosts in your setup. So if you had A, B, C, and D, you'd set up >> agreements between A-B, A-C, A-D, B-C, B-D, and C-D. >> > > > The documentation contradicts you. Look at the second figure in the > "Multi-Master Replication" section of the admin manual (hard to see), > and the section "Configuring 4-Way Multi-Master Replication" several > pages below it: > http://www.redhat.com/docs/manuals/dir-server/ag/7.1/replicat.html#1101818 > > The admin manual suggests a ring topology (and two agreements per set of > peers) for multi-master agreements. You should have agreements between > A->B, A->D, B->A, B->C, C->B, C->D, D->C, and D->A. Ring-topology survives 1 server failure, but not two. You need to understand your high-availability requirements to decide which is right for you. Full-mesh replication supports 2 servers failing at the same time, but increases replication traffic. Mininum level of agreements for 4-way MMR: 1 <-> 2 1 <-> 3 2 <-> 4 Maximum level of agreements (full-mesh) for 4-way MMR (each machine replicates to 3 targets): 1 <-> 2 1 <-> 3 1 <-> 4 2 <-> 3 2 <-> 4 3 <-> 4 Again, it's much easier to visualize when you draw numbered boxes on paper and connect the dots :-) The systems I design require high-availability for writes, so I use full-mesh MMR. -- mike
