text: Figure 7-5 Striped extent allocation 
  
  (cid:2) A*sequential*volume contains a volume copy that has extents allocated sequentially on 
  one MDisk. 
  
  (cid:2)*Image-mode*volume is a special type of volume that has a direct one-to-one mapping to 
  one (image mode) MDisk. 
  
  For striped volumes, the extents are allocated from the set of MDisks (by default, all MDisks in 
  the storage pool): 
  
  (cid:2) An MDisk is picked by using a pseudo-random algorithm and an extent is allocated from 
  this MDisk. This approach minimizes the probability of triggering the*striping effect*, which 
  might lead to poor performance for workloads that generate many metadata I/O, or that 
  create multiple sequential streams. 
  
  (cid:2) All subsequent extents (if required) are allocated from the MDisk set by using round-robin 
  algorithm. 
  
  (cid:2) If an MDisk has no free extents when its turn arrives, the algorithm moves to the next 
  MDisk in the set that has a free extent. 