HP XP P9500 Storage - Manual (Page 17)

Figure 11 Creating Cnt Ac-S Z pair in Compatible FlashCopy pair
Figure 12 Dataset copying
Comparison of Results of Cnt Ac-S Z Pair operations
Cnt Ac-S Z pair operations sometimes produce different results depending on whether differential
data of the Cnt Ac-S Z pair are stored in units of tracks or cylinders. See the following table.
FlashCopy to PPRC Primary Volume function 17