It might be helpful if you could clarify your question.
From a technical point of view a disk shelf can be populated with all kind of drives (SSD, SAS, SATA) as long as they fit into the slots, the controller supports the drives and - important - as long as the vendor supports mixing drives with different speeds in the same shelf. Some vendors do not support mixing drives, due to e.g. vibrations of drives with different speed which may cause the drives to fail.
André
