text: an increase in response times on volumes that use the same storage. Also, host formatting 
  time is likely to increase, compared to a system that does not advertise support the SCSI 
  Unmap command. 
  
  If you use Data Reduction Pools, thin-provisioned back-end that supports Unmap, or Flash 
  Core Modules, it is recommended to turn on SCSI Unmap support. 
  
  If only standard pools are configured and back-end is traditional (fully provisioned), you might 
  consider keeping host Unmap support switched off because you do not see any 
  improvement. 
  
  To check and modify current setting for host SCSI Unmap support, use the**lssystem**and 
  **chsystem**CLI commands, as shown in Example 10-8. 
  
  Example 10-8 Turning host unmap support on 
  
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              [html]<thead><tr><td>IBM Storwi ze : ITS0V7K : superuser > 1ssystem</td><td>grep host_unmap</td></tr></thead><tbody><tr><td>host_unmap_off</td><td>IBM_Storwi ze : ITS0V7K : superuser > chsystem</td></tr><tr><td>- hostunmap on</td></tr><tr></tr></tbody>
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