This configuration is one of the R2 PDomain configurations (see Understanding Dual Compute Server Configurations (R2 Configurations)).
The R2-4 PDomain configuration has these characteristics:
Populated PDomains 0 and 1 in compute server 1, and populated PDomain 0 in compute server 2
One to four CMIOUs in each populated PDomain
This figure shows the CMIOU slots on each PDomain in this configuration.