text: When planning storage pool layout, consider the following aspects: 
  
  (cid:2) Pool extent size: 
  
  – Generally, use 128 MiB or 256 MiB. The IBM Storage Performance Council (SPC) 
  benchmarks use a 256 MiB extent. 
  
  – Pick the extent size and then use that size for all storage pools. 
  
  – You cannot migrate volumes between storage pools with different extent sizes. 
  
  However, you can use volume mirroring to create copies between storage pools with 
  different extent sizes. 
  
  (cid:2) Storage pool reliability, availability, and serviceability (RAS) considerations: 
  
  – The number and size of storage pools affects system availability. The use of larger 
  
  number of smaller pools reduces the failure domain in case one of pools goes offline. 
  However, increased number of storage pools introduces management overhead, 
  effects storage space use efficiency, and is subject to the configuration maximum limit. 
  
  – An alternative approach is to create few large storage pools. All MDisks that constitute 
  each of the pools should have the same performance characteristics. 
  
  – The storage pool goes offline if an MDisk is unavailable, even if the MDisk has no data 
  on it. Do not put MDisks into a storage pool until they are needed. 