text: For clustered Storwize V7000 (two or more I/O Groups) systems that do not virtualize 
  external storage (and therefore cannot place a quorum disk on an external MDisk), 
  generally use IP quorum device to reduce the risk of outage in case of a split-brain cluster. 
  
  For HyperSwap systems, it is recommended to have at least two independent IP quorum 
  devices defined to prevent the active quorum device placement in one of sites that hold 
  Storwize V7000 HyperSwap storage components. Also, make sure that at least one 
  quorum drive is in each site. 
  
  The IP quorum device acts only as a tie breaker in case of a split-brain cluster scenario. 
  Quorum disks are still required to store cluster state. 
  
  (cid:2) Failure domain sizes 
  
  Failure of an MDisks takes offline the entire storage pool that contains this MDisk. To 
  reduce the effects of an MDisk failure, consider reducing the number of back-end storage 
  systems per storage pool, and increasing the number of storage pools and reducing their 
  size. This configuration limits the maximum performance of the pool (fewer back-end 
  systems to share the load), increases storage management effort, can lead to less 
  efficient storage capacity consumption. It also might be subject to limitation by system 
  configuration maximums. 