text: Figure 6-35 Single drive failure with DRAID 6 (for simplification, not all packs are shown) 
  
  This model addresses the main disadvantages of traditional RAID: 
  
  (cid:2) In case of a drive failure, data is read from many drives and written to many drives. This 
  
  process minimizes the effect on performance during the rebuild process. Also, it 
  significantly reduces rebuild time. (Depending on the distributed array configuration and 
  drive sizes the rebuild process can be up to 10 times faster.) 
  (cid:2) Spare space is distributed throughout the array. So, more drives are processing I/O, and 
  no spare drives are idling. 
  
  IBM Storwize V7000 DRAID implementation has the following additional advantages: 
  
  (cid:2) In case of a drive failure, only the actual data is rebuilt. Space that is not allocated to 
  volumes is not re-created to the spare regions of the array. 
  (cid:2) Arrays can be much larger than before and can span many more drives, therefore 
  
  improving the performance of the array. The maximum number of drives a Distributed 
  RAID can contain is 128. 
  
  The following are the minimum number of drives that are needed to build a Distributed Array: 
  
  (cid:2) Six drives for a Distributed RAID6 array 
  (cid:2) Four drives for a Distributed RAID5 array 