text: If a thin-provisioned volume does not have enough real capacity for a write operation, the 
  volume is taken offline and an error is logged (error code 1865, event ID 060001). Access to 
  the thin-provisioned volume is restored by increasing the real capacity of the volume, which 
  might require increasing the size of the storage pool from which it is allocated. Until this time, 
  the data is held in the Storwize V7000 cache. Although in principle this situation is not a data 
  integrity or data loss issue, you must not rely on the Storwize V7000 cache as a backup 
  storage mechanism. 
  
  Space is not allocated on a thin-provisioned volume if an incoming host write operation 
  contains all zeros. 
  
  **Important:**Set and monitor a warning level on the used capacity so that you have 
  adequate time to respond and provision more physical capacity. 
  
  Warnings must not be ignored by an administrator. 
  
  Consider the use of the autoexpand feature of the thin-provisioned volumes to reduce 
  human intervention required to maintain access to thin-provisioned volumes. 
  
  When you create a thin-provisioned volume, you can choose the grain size for allocating 
  space in 32 kibibytes (KiB), 64 KiB, 128 KiB, or 256 KiB chunks. The grain size that you select 
  affects the maximum virtual capacity for the thin-provisioned volume. The default grain size is 
  256 KiB, which is the preferred option. If you select 32 KiB for the grain size, the volume size 
  cannot exceed 260,000 gibibytes (GiB). The grain size cannot be changed after the 
  thin-provisioned volume is created. 