text: **3.6.4 Back-end storage zones**
  
  Create one Storwize V7000*storage zone*for each back-end storage subsystem that is 
  virtualized by the Storwize V7000. 
  
  A storage controller can present LUNs to the Storwize V7000 (as MDisks) and to other hosts 
  in the SAN. However, if this is the case, it is better to allocate different ports on the back-end 
  storage for communication with Storwize V7000 and for hosts traffic. 
  
  All nodes in a system must connect to the same set of storage system ports on each device. 
  A system that contains any two nodes that cannot connect to the same set of storage-system 
  ports is considered degraded. In this situation, a system error is logged that requires a repair 
  action. This rule can have important effects on a storage system. For example, an IBM 
  DS4000® series controller can have exclusion rules that determine to which host bus adapter 
  (HBA) worldwide node names (WWNNs) to which a storage partition can be mapped. 
  
  In the example that is shown in Figure 3-3, all back-end storage ports are connected to all 
  Storwize V7000 ports. Therefore, each port on back-end storage is zoned to all ports of the 
  Storwize V7000 that are connected to the same fabric. For clarity, the figure shows only paths 
  for one back-end storage port per controller: Port P1 in Fabric 0 and port P4 in Fabric 1. 