Designing Disaster Tolerant High Availability Clusters, 10th Edition, March 2003 (B7660-90013)

Building a Metropolitan Cluster Using MetroCluster/SRDF
Preparing a Cluster for MetroCluster/SRDF
Chapter 4142
Setting up Hardware for M by N Configurations
You can configure up to four Symmetrix disk arrays in the following
combinations:
An array in Data Center A connected to one array in Data Center B.
An array in Data Center A connected to two arrays in Data Center B.
Two arrays in Data Center A connected to an array in Data Center
B.
Two arrays in Data Center A connected to two arrays in Data Center
B.
WARNING M by N configurations cannot be used with R1/R2 swapping.