text: Figure 2-11 IBM Spectrum Virtualize virtualization components 
  
  **2.5.16 Volumes**
  
  A volume is a logical disk that is presented to a host system by the clustered system. In our 
  virtualized environment, the host system has a volume mapped to it by IBM Storwize V7000. 
  IBM Spectrum Virtualize translates this volume into several extents, which are allocated 
  across MDisks. The advantage of storage virtualization is that the host is “decoupled” from 
  the underlying storage, so the virtualization appliance can move the extents without affecting 
  the host system. 
  
  The host system cannot directly access the underlying MDisks in the same manner as it can 
  access RAID arrays in a traditional storage environment. 
  
  The following types of volumes are available: 
  
  (cid:2) Striped 
  
  A striped volume is allocated one extent in turn from each MDisk in the storage pool. This 
  process continues until the space required for the volume is satisfied. 
  
  It is also possible to supply a list of MDisks to use. 