text: When a data reduction pool is created, the system monitors the pool for reclaimable capacity 
  from host unmap operations. This capacity can be reclaimed by the system and redistributed 
  into the pool. Create volumes that use thin provisioning or compression within the data 
  reduction pool to maximize space within the pool. 
  
  **10.4.3 Implementing DRP with compression and deduplication**
  
  The implementation process for DRPs is similar to standard pools, but has its own specifics. 
  
  **Creating pools and volumes**
  To create a DRP, select**Data Reduction Enable**in the Create Pool dialog, which is available 
  be clicking**Pools**→**Pools**. For more information about how to create a storage pool and 
  populate it with MDisks, see Chapter 6, “Storage pools” on page 191. 
  
  There is a maximum number of four DRPs in a system. When this limit is reached, no other 
  DRPs can be created. 
  
  A DRP uses metadata. Even when there are no volumes in the pool, some of the space of the 
  pool is used to store the metadata. Regardless of the type of volumes the pool contains, 
  metadata is always stored separate from customer data. 
  
  Metadata capacity depends on the total capacity of a storage pool and on a pool extent size. 
  This should be considered when planning capacity. 