Disk class is an attribute of disk drive modules, array sites, and arrays. The disk class attribute distinguishes between different classes of disk drives, such as enterprise drives and near-line drives, each with different performance and reliability characteristics. When you create an array with multiple array sites, the disk class must be the same for all array sites in the array that you are creating to ensure that the array maintains the same performance and reliability characteristics of the disk drive modules.
If you want to create an array from multiple array sites, you must select array sites that have the same disk class. If you want to create arrays from array sites that have different disk classes, you must create separate arrays for each disk class.