text: The real capacity of a thin-provisioned volume can be changed if the volume is not in image 
  mode. Thin-provisioned volumes use the grains of real capacity that is provided in ascending 
  order as new data is written to the volume. If the user initially assigns too much real capacity 
  to the volume, the real capacity can be reduced to free storage for other uses. 
  
  **Note:**Thin-provisioning is supported in standard pools and data reduction pools. However, 
  data reduction pools support reclaiming capacity when it is no longer used by host data 
  and then can redistribute it automatically for other uses. For more information, see 7.1.11, 
  “Capacity reclamation” on page 254. 
  
  A thin-provisioned volume can be configured to*autoexpand*. This feature causes the IBM 
  Spectrum Virtualize to automatically add a fixed amount of extra real capacity to the 
  thin-provisioned volume as required. Autoexpand does not cause the real capacity to grow 
  much beyond the virtual capacity. Instead, it attempts to maintain a fixed amount of unused 
  real capacity for the volume, which is known as the*contingency capacity*. 
  
  The contingency capacity is initially set to the real capacity that is assigned when the volume 
  is created. If the user modifies the real capacity, the contingency capacity is reset to be the 
  difference between the used capacity and real capacity. 