The following table describes common storage devices

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The following table describes common storage devices: Device Type Description
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Hard disk drive (HDD) A hard disk is a thick magnetic disk encased in a thicker protective shell. A hard disk consists of several aluminum platters, each of which requires a read/write head for each side. All of the read/write heads are attached to a single access arm to prevent them from moving independently. Each platter has circular tracks that cut through all of the platters in the drive to form cylinders . The spinning of the platters is referred to as revolutions per minute (RPM). The higher the revolutions per minute, the faster the data can be accessed. Standard hard drives are categorized as follow: 5400 rpm (inexpensive HDD) 7200 rpm (good quality HDD) 10,000 rpm (expensive HDD) Some of the advantages of hard disks are: They have lots of storage (starting at 16 GB up to several TB). They are significantly faster than floppy disks. The cost per MB is cheap. Some of the disadvantages of hard disks are: Many hard disks are internal devices, though you can get external enclosures. They are prone to failure. They are vulnerable to physical damage (e.g., when dropped). Solid state drive (SSD) A solid state drive is a flash device with a storage capacity similar to a small hard drive. Solid state drives are used as replacements for hard disk drives for storing operating system, application, and data files. Some advantages of solid state drives: They are faster than hard drives. They have no moving parts. They have lower power consumption than hard drives (good for laptops). They are less susceptible to physical damage (from dropping) and immune from magnetic fields. They are smaller and lighter than hard drives The main disadvantage currently for solid state drives is cost--they are several times more expensive than comparable hard drives. However, their advantages make them a good choice, especially for portable devices. Flash devices Flash memory cards store information using programmable, non-volatile flash memory. Some of the advantages of flash devices are: The memory is re-programmable. They can retain content without power. They are optimal for use in devices like cameras. They are highly portable. They have a larger capacity than CDs and DVDs. They have relatively fast memory access. Some of the disadvantages of flash devices are: Their storage capacity is not yet comparable to the capacity of modern hard disks. Different memory card formats require different readers. Common flash memory cards include: CompactFlash cards eMMC cards SD cards SSD cards MiniSD cards MicroSD cards xD cards
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Hybrid cards (combines SSD and HDD technology) Memory sticks Optical disc Optical discs such as CDs, DVDs, and Blu-ray discs are a storage medium that uses lasers for both reading and writing information. Optical discs store information through pits in their reflective coating. As the disc spins, the optical drive sends laser optics to the disk, and receives the stored information through the deflected output.
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