268 Implementing the IBM Storwize V7000 with IBM Spectrum Virtualize V8.2.1
This pane includes the following options:
/SM590000Real capacity: Real capacity of the volume, which is specified as percentage of the virtual 
capacity or in bytes.
/SM590000Automatically expand: Whether to automatically expand the real capacity of the volume if 
needed; defaults to Enabled.
/SM590000Warning threshold: Whether a warning message is sent and at what percentage of filled 
virtual capacity; defaults to Enabled, with a warning threshold set at 80%.
/SM590000Thin-Provisioned Grain Size: Allows you to define the grain size for the thin-provisioned 
volume; defaults to 256 KiB.
Compressed pane
If you choose to create a compressed volume, a Compressed pane is displayed, as shown in 
Figure 7-21.
Figure 7-21   Compressed pane
This pane gives the following options:
/SM590000Real capacity: Real capacity of the volume, which is specified as percentage of the virtual 
capacity or in bytes.
/SM590000Automatically expand: Whether to automatically expand the real capacity of the volume if 
needed; defaults to Enabled.
/SM590000Warning threshold: Whether a warning message is sent, and at what percentage of filled 
virtual capacity; defaults to Enabled, with a warning threshold set at 80%.
You cannot specify grain size for a compressed volume.
Important: If you do not use the autoexpand feature, the volume goes offline if it 
receives a write request after all real capacity is allocated. 
The default grain size is 256 KiB. The optimum choice of grain size is dependent upon 
volume use type. Consider the following points:
/SM590000If you are not going to use the thin-provisioned volume as a FlashCopy source or 
target volume, use 256 KiB to maximize performance. 
/SM590000If you are going to use the thin-provisioned volume as a FlashCopy source or target 
volume, specify the same grain size for the volume and for the FlashCopy function.
/SM590000If you plan to use EasyTier with thin-provisioned volumes, see the IBM Support 
article Performance Problem When Using EasyTier With Thin Provisioned Volumes.