432 Implementing the IBM Storwize V7000 with IBM Spectrum Virtualize V8.2.1
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:
/SM590000IBM A9000 V12.1.0 and above
/SM590000FlashSystem 900 V1.4
/SM590000FlashSystem 9000 AE2 expansions
/SM590000IBM Storwize family system with code V8.1.0 and above
/SM590000Pure 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.
It is not recommended to use “DRP above DRP”, when the back-end system belongs to the 
IBM Spectrum Virtualize family. With this configuration, implement fully allocated MDisks on 
the back-end and configure space efficiency features on IBM Storwize V7000 with DRPs.
The IBM Storwize V7000 storage administrator can monitor space use usage on 
thin-provisioned MDisks by using one of the following methods:
/SM590000GUI Dashboard, as shown in Figure 10-19.
Figure 10-19   Dashboard button for overprovisioned storage monitoring
For more information, see Chapter 5, “Graphical user interface” on page 131.