A block diagram showing 2 Sun fire E6900 systems, each with 2 partitions, a and b. In the first system, each partition has 1 domain. Partition a has active domain connections to boards 0,1, 2 and 3. Partition b has active domain connections to boards 4 and 5. Both partitions a and b have inactive logical connections to the other partition boards. Partition a has inactive logical connections to boards 4 and 5. The second diagram is similar to the first but partition a has 2 domains.