text: These numbers estimate the amount of traffic between the two clustered systems when no 
  I/O is taking place to mirrored volumes. Half of the data is sent by each of the systems. The 
  traffic is divided evenly over all available intercluster links. Therefore, if you have two 
  redundant links, half of this traffic is sent over each link. 
  
  The bandwidth between sites must be sized to meet the peak workload requirements. You 
  can estimate the peak workload requirement by measuring the maximum write workload 
  averaged over a period of 1 minute or less, and adding the heartbeat bandwidth. Statistics 
  must be gathered over a typical application I/O workload cycle, which might be days, weeks, 
  or months, depending on the environment in which the Storwize V7000 is used. 
  
  When planning the inter-site link, consider also the initial sync and any future resync 
  workloads. It might be worthwhile to secure additional link bandwidth for the initial data 
  synchronization. 
  
  If the link between the sites is configured with redundancy so that it can tolerate single 
  failures, you must size the link so that the bandwidth and latency requirements are met even 
  during single failure conditions. 
  
  When planning the inter-site link, make a careful note whether it is dedicated to the 
  inter-cluster traffic or is going to be used to carry any other data. Sharing link with other traffic 
  (for example, cross-site IP traffic) might reduce the cost of creating the inter-site connection 
  and improve link utilization. However, doing so might affect the links’ ability to provide the 
  required bandwidth for data replication. 