For this example, the emulation type of the mainframe volume is 3390-3. Recall the formula for calculating the required amount of differential tables per migration pair:
(X (number of volume cylinders) + Y (number of control cylinders)) × 15 / Z (number of slots that can be managed by a differential table)
For a 3390-3 device:
- X = 3,339
- Y = 21
- Z = 20,448
Calculation:
(3,339 + 21) × 15 / (20,448) = 2.464788732
When you round up 2.464788732 to the nearest whole number, it becomes 3. Therefore, the total number of required differential tables for each migration pair is 3 when the device emulation type is 3390-3.
One pair table can be used for 36 differential tables. Therefore, the number of pair tables for one migration pair is 1 when the emulation type is 3390-3. Two pair tables are used when the emulation type is 3390-M, and the number of volume cylinders is the default number.