text: This feature is turned on by default. It is recommended to keep back-end unmap enabled, 
  especially if a system is virtualizing a thin-provisioned storage controller or uses Flash Core 
  Modules. 
  
  To verify that sending unmap commands to back-end is enabled, use the CLI command 
  **lssystem**, as shown in Example 10-7. 
  
  Example 10-7 Verifying back-end unmap support status 
  
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          <table frame="hsides" rules="groups" width="100%%">
              [html]<thead><tr><td>IBM_Storwi ze : 1TS0V7K : superuser > 1ssystem</td><td>grep backend_unmap</td></tr></thead><tbody><tr><td>backend_unmap_on</td></tr></tbody>
          </table> </body> </html>