DS8000® storage units use device adapters to provide communication between the storage images and the storage devices.
Each storage image requires at least one pair of device adapters. This means that Models 921, 931, 932, and 922 require at least one pair of device adapters, and a Model 9A2 or a Model 9B2 requires at least two pairs.
Model DS8870 requires at least one pair of device adapters. With a device adapter pair configuration, the DS8000 can access any disk drive from either of two paths. This configuration provides fault tolerance and enhanced availability.