Internet Hard Drives

An Internet hard drive is storage space on a server that is accessible from the Internet. In most cases, a computer user subscribes to the storage service and agrees to rent a block of storage space for a specific period of time. Instead of sending e-mail attachments to share with family and friends, you might simply post the files to your Internet hard drive and then allow them to be viewed or retrieved by others. You might save backup copies of critical files or all the data on your hard disk to your Internet hard drive. The key advantage of this type of remote storage is the ability to access data from multiple locations. You can access your files from any device that can connect with the Internet, so everything you store on the site is available to you at any time. Some disadvantages are that your data may not be secure; the storage device might become corrupt, causing you to lose your data; and the company offering the Internet storage may go out of business.

Transfer Performance

Transfer performance refers to how quickly the disk transfers data from the disk to memory. One way disk manufacturers improve transfer performance is to increase the speed at which the disk spins, which makes data available more quickly to the read/write heads. Another way is to improve the spacing of data on the disk so that the heads can retrieve several blocks of data on each revolution. Another way to improve hard disk performance is with a type of cache memory called disk cache. A disk cache is a type of RAM that stores the program instruction and data you are working with. When the CPU needs to get information, it looks in the disk cache first. If it doesn’t find the information it needs, it retrieves the information from the hard disk.

Hard Disk Drive

On almost all computers, the hard disk drive is by far the most important storage device. A hard disk drive (or simply hard disk) is a high-capacity, high-speed storage device that usually consists of several fixed, rapidly rotating disks called platters. The computer’s hard disk also referred to as online storage. Online storage (also called primary storage) consists of the storage devices that are actively available to the computer system and that do not require any action on the part of the user. Hard disks can also be categorized as random access or magnetic storage device. A random access storage device can go directly to the requested data without having to go through a linear search sequence. Magnetic storage devices use disks that are coated with magnetically sensitive material. With magnetic storage devices, an electromagnetic called a read/write head moves across the surface of a disk and records information by transforming electrical impulses into a varying magnetic field. As the magnetic material pass beneath the read/write head, this varying field forces the particles to rearrange themselves in a meaningful pattern of positive and negative magnetic indicators. This action is called writing. When reading, the read/write head senses the recorded pattern and transforms this pattern into electrical impulses. A hard disk contains two or more vertically stacked platters, each with, two read/write heads (one for each side of the disk). The platters spin so rapidly that the read/write head floats on a thin cushion of air, at a distance 300 times smaller than the width of a human hair. To protect the platter’s surface, hard disks are enclosed in a sealed container. Two or more sector combines to form a cluster.