text: Apply the following general guidelines for back-end storage subsystem configuration 
  planning: 
  
  (cid:2) In the SAN, storage controllers that are used by the Storwize V7000 clustered system 
  
  must be connected through SAN switches. Direct connection between the Storwize V7000 
  and the storage controller is not supported. 
  
  (cid:2) Enhanced Stretched Cluster configurations have additional requirements and 
  
  configuration guidelines. For more information about performance and preferred practices 
  for the Storwize V7000, see IBM System Storage SAN Volume Controller and Storwize 
  V7000 Best Practices and Performance Guidelines, SG24-7521. 
  
  **MDisks within storage pools:**Software versions 6.1 and later provide for better load 
  distribution across paths within storage pools. 
  
  In previous code levels, the path to MDisk assignment was made in a round-robin fashion 
  across all MDisks that are configured to the clustered system. With that method, no 
  attention is paid to how MDisks within storage pools are distributed across paths. 
  Therefore, it was possible and even likely that certain paths were more heavily loaded than 
  others. 
  
  Starting with software version 6.1, the code contains logic that considers which MDisks are 
  provided by which back-end storage systems. Therefore, the code more effectively 
  distributes active paths based on the storage controller ports that are available. 