text: IBM Storwize V7000 detects if the MDisk is thin-provisioned, its total physical capacity, used, 
  and remaining physical capacity. It detects if SCSI Unmap commands are supported by 
  back-end. 
  
  By sending SCSI Unmap commands to thin-provisioned MDisks, IBM Storwize V7000 marks 
  data that is no longer in use. Then, the garbage collection processes on the back-end can 
  free unused capacity and reallocate it to free space. 
  
  At the time of this writing, the following back-end controllers are supported by thin-provisioned 
  MDisks: 
  
  (cid:2) IBM A9000 V12.1.0 and above 
  (cid:2) FlashSystem 900 V1.4 
  (cid:2) FlashSystem 9000 AE2 expansions 
  (cid:2) IBM Storwize family system with code V8.1.0 and above 
  (cid:2) Pure Storage 
  
  It is recommended to assign thin-provisioned MDisks to DRPs. To avoid overcommitting, 
  assume a 1:1 compression ratio in back-end storage. Small, extra savings are realized from 
  compressing metadata. 
  
  Fully allocated volumes that are above thin-provisioned MDisks configurations must be 
  avoided or used with extreme caution because it can lead to overcommitting back-end 
  storage. 