In a DDP configuration, the available capacity per drive is less than the drive capacity because of the system management area. The unusable capacity varies depending on the drive capacity. The maximum is about 2 % of the drive capacity.
The number of drives that DDP contains can be changed in one-drive increments, and the optimal capacity can be purchased to accommodate the required capacity for users. The following figure shows the number of drives and capacity efficiency for the required capacity for RAID6 (1 drive = 14TB). The number of drives relative to the data capacity has a linear slope.
