text: **2.5.15 Storage pool**
  
  A storage pool is a collection of MDisks that are grouped to provide capacity for volumes. All 
  MDisks in the pool are split into extents with the same size. Volumes are then allocated out of 
  the storage pool and are mapped to a host system. 
  
  **IBM Storwize V7000 object names:**The names*must*begin with a letter and can be a 
  maximum of 63 characters. Valid characters for names are uppercase letters (A-Z), 
  lowercase letters (a-z), digits (0 - 9), underscore (_), period (.), hyphen (-), and space. The 
  names must not begin or end with a space. 
  
  MDisks can be added to a storage pool at any time to increase the capacity of the storage 
  pool. MDisks can belong in only one storage pool, and only MDisks in unmanaged mode can 
  be added to the storage pool. When an MDisk is added to the storage pool, the mode 
  changes from unmanaged to managed (and vice versa when you remove it). 
  
  Each MDisk in the storage pool is divided into several extents. The size of the extent is 
  selected by the administrator at creation time of the storage pool, and cannot be changed 
  later. The size of the extent ranges from 16 MB - 8 GB. The default extent size in V8.1 is 
  1024 MB. 