text: The extent size directly affects the maximum volume size and storage capacity of the 
  clustered system. A system can manage 4 million (4 x 1024 x 1024) extents. For example, a 
  system with a 16 MB extent size can manage up to 16 MB x 4 MB = 64 TB of storage. 
  
  Use the same extent size for all storage pools in a clustered system, which is a prerequisite 
  for supporting volume migration between two storage pools. If the storage pool extent sizes 
  are not the same, you must use volume mirroring to copy volumes between storage pools. 