RAID products are computer hardware components and modules that use a redundant array of independent or inexpensive disks (RAID) to store the same data in different places on multiple hard drives in order to improve speed, performance and data recoverability. There are several types of RAID products. RAID controllers are computer boards or standalone modules that use special protocols to control RAID disc arrays, groups of storage discs that function as single, large and fast disk drives. Bus-based RAID controllers are connected to RAID arrays and installed on personal computers (PCs) and servers. They are interfaced to RAID arrays via small computer system interface (SCSI), integrated drive electronics (IDE), or advanced technology attachment (ATA) protocols. Integrated RAID controllers are built into the computer motherboard and function like a bus-based add-in card. External RAID controllers are separate devices for higher-end systems. Unlike bus-based RAID controllers, external RAID controllers are removed completely from the larger system. They are housed in a separate hardware structure (box) and use SCSI to present the logical drives of the array to the server.