Calculating the number of cache management devices required for DP-VOLs

A volume that is not a DP-VOL requires one cache management device. The number of cache management devices that a DP-VOL requires depends on the capacity of the V-VOL (capacity of the user area) and the maximum capacity of the cache management device.

The following table explains the relationship between the pool volume attribute and the maximum capacity of the cache management device.

	Maximum capacity of cache management device
Pool attribute of V-VOL	MB (TB)	Blocks
Internal volume	3,145,548 MB (2.99 TB)	6,442,082,304 blocks
External volume	3,145,548 MB (2.99 TB)	6,442,082,304 blocks

Use the following formula to calculate the number of cache management devices that a DP-VOL requires. In this formula, the user-specified capacity is the user area capacity of a V-VOL.

ceiling(user-specified-capacity / max-capacity-of-cache-management-device)

where

• ceiling: The value enclosed in ceiling( ) must be rounded up to the nearest whole number.