text: Figure 7-7 Conceptual diagram of thin-provisioned volume 
  
  Thin-provisioned volumes store user data and metadata, and each grain of user data requires 
  metadata to be stored. Therefore, the I/O rates that are obtained from thin-provisioned 
  volumes are lower than the I/O rates that are obtained from fully allocated volumes. 
  
  The metadata storage used is never greater than 0.1% of the user data. The resource usage 
  is independent of the virtual capacity of the volume. 
  
  **Thin-provisioned volume format:**Thin-provisioned volumes do not need formatting. A 
  read I/O, which requests data from not allocated data space, returns zeros. When a write 
  I/O causes space to be allocated, the grain is “zeroed” before use. 