Secondary Storage

File Compression


Compression is useful because it helps reduce the consumption of expensive resources, such as hard disk space or transmission bandwidth. On the downside, compressed data must be decompressed to be used, and this extra processing may be detrimental to some applications.

In computer science and information theory, data compression or source coding is the process of encoding information using fewer bits (or other information-bearing units) than an unencoded representation would use, through use of specific encoding schemes.



Head Crash

 A head crash usually means that the head has scratched or burned the disk. In a hard disk drive, the head normally hovers a few microinches from the disk. If the head becomes misaligned or if dust particles come between it and the disk, it can touch the disk. When this happens, you usually lose much of the data on the hard disk and will need to replace both the head and the disk. Head crashes are less common for floppy disks because the head touches the disk anyway under normal operation.

Another term for head crash is disk crash.

                                     Optical Disk Drive

 A storage medium from which data is read and to which it is written by lasers. Optical disks can store much more data up to 6 gigabytes (6 billion bytes) -- than most portable magnetic media, such as floppies. There are three basic types of optical disks:  CD-ROM, WORM, erasable.

These three technologies are not compatible with one another; each requires a different type of disk drive and disk. Even within one category, there are many competing formats, although CD-ROMs are relatively standardized.

Solid-State Storage

is a nonvolatile, removable storage medium that employs integrated circuits rather than magnetic or optical media. It is the equivalent of large-capacity, nonvolatile memory. Examples include flash memory Universal Serial Bus (USB) devices and various proprietary removable packages intended to replace external hard drives.

                                     
                                      Internet Hard Drive

Since the advent of digital media, there has been a need to store and retrieve media. Internet hard drives have served to meet this need, offering a creative new solution to the issue of data storage.

The sole purpose of an Internet hard drive is to offer a means of accessing your computer files (pictures, documents, music, videos, etc.) from any computer, as long as that computer has access to the Internet.

Unlike your local hard drive, which may have a limited storage capacity, a competitive Internet hard drive provider will offer virtually unlimited disk space.