What is storage hierarchy?
Computer storage devices include any hardware that stores data. The most common type of storage device is a hard drive. The computer's primary hard drive stores the operating system, applications, and files and folders for users of the computer.While the hard drive is the most known of all storage devices, other common types exist as well. Flash memory devices, such as USB drives and iPod nanos are popular ways to store data in a small, portable format. Other types of flash memory, such as compact flash and SD cards, are popular ways to store digital camera images.External hard drives which use USB and Firewire sockets are common too. These types of drives are often used for video and photo storage, backing up internal hard drives, or for simply adding extra storage. Tape drives are another type of storage device. They are an older technology and use reels of tape to store data. They are typically used for backing up data.Storage device hierarchy is comprised of the settings that determine the order that the storage devices are accessed. While that has traditionally been determined by the cable positions and jumpers on the drives, this is now a CMOS setting as well. The reason for that is because there are so many different types of storage devices, and any of them can be bootable. So without such a CMOS setting, there is no way for the bootloader and OS to know the order of the drives.