secondary by liuhongmeiyes


 Ahijah Lane
    Secondary Storage
A storage medium that holds information
  until it is deleted or overwritten.

                QuickTim e™ a nd a
     TIFF (Un com pre ssed) decom presso r
        are neede d to see this p icture.
 Magnetic Tape Storage:
- is a 1/4 inch or 1/2 inch ribbon
  of plastic material on which data is recorded. It
  reads, writes and erases data on tapes.
- Magnetic tapes are erasable, reusable and
  durable and made to store large quantities of
Magnetic Disk Storage:
- Magnetic disks are the most widely used storage
medium for computers.
- It offers high storage capacity, reliability, and the
capacity to directly access stored data while
holding more data.
     Types of Magnetic Disk Storage:
• Diskettes: Introduced in early 1970s by IBM as a new type of
  secondary storage. Originally they were thin and flexible which gave them
  the name floppy disks.
       • used as the principle medium of secondary storage for personal

• Hard Disks: Hard disks provide larger and faster secondary
  storage capabilities than diskettes. Usually hard disks are permanently
  mounted inside the computer with 2-4 disk drives.

• Disk Cartridges: Offer the storage and fast access of hard
  disks and the portability of diskettes.
       • More secure because the disk cartridge can be removed and locked up
         leaving no data on the computer.
Recovery Devices:
• Backup: creating a copy of important
  programs and data. To backup diskettes, copy the
  data from one to the other. Diskettes are frequently
  used to backup important files on hard drives of
  personal computers.

• Data Recovery: There does exist certain
  software programs that can recover data and
  programs that have been "lost." Often your operating
  system will be able to do this.

Storage      Speed       Capacity     Relative   Permanent?
                                      Cost ($)
Hard Disk   Moderate     Very High    Very Low      Yes

Registers    Fastest      Lowest      Highest       No

 Floppy     Very Slow      Low          Low         Yes
  RAM       Very Fast   Low/Moderat    High         No
  Benefits of Secondary Storage:
• Capacity. Organizations may store the equivalent of a
  roomful of data on sets of disks that take up less space than a

• Reliability. Data in secondary storage is basically safe,
  since secondary storage is physically reliable.

• Convenience. With the help of a computer, authorized
  people can locate and access data quickly.
• Cost. It is less expensive to store data on tape or disk than
  filing cabinets, but the greatest savings can be found in the
  speed and convenience of filing and retrieving data.

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