Typically a disk array provides increased availability, resiliency, and maintainability by using existing components (controllers, power supplies, fans, etc.), often up to the point where all single points of failure (SPOFs) are eliminated from the design. Additionally, disk array components are often hot-swappable.
Typically, disk arrays are divided into categories:
Primary vendors of storage systems include Coraid, Inc., DataDirect Networks, Dell EMC, Hewlett Packard Enterprise, Hitachi Data Systems, Huawei, IBM, Infortrend, NetApp, Oracle Corporation, Panasas, Pure Storage and other companies that often act as OEMs for the above vendors and do not themselves market the storage components they manufacture.