TEACHERMR. WIEMER

BVFSemester-1

StorageAnd

MultimediaSecondary Storage

What is the Objective of storage media

manufacture?Imagine that your computer without memory..!

You can create a complete library containing all the books it contains the largest library in theworld and carryin your handanywhere.

Benefits ofSecondary Storage

• Space• Reliability• Convenience• Economy

• You can store files and photos fill the large room in one storage.

• In the floppy disk save the equivalent of 500 pages printed.

• In the optical disc can save the equivalent of 500 books

Space

Can you imagine how many books you

can save on your hard drive?

Reliability

• Data in secondary storage is relatively safe.

• Secondary storage is highly reliable• More difficult for untrained people

to tamper with data stored on disk

Convenience

• Authorized users can easily and quickly locate data stored on the computer

Economy• Several factors create significant savings

in storage costs Less cost to store data on disks Reliable

and safe. Less time, Greater speed and

convenience in filing and retrieving data

(save time & money)

Magnetic Disk StorageData represented as magnetized spots on surface of spinning disk• Spots on disk converted to electrical

impulsesPrimary types• Diskette• Hard Disk

Diskettes• Made of flexible Mylar and coated with iron oxide.• Has protection of rigid plastic jacket.• 3 ½” diskette.• Holds 1.44 MB of data.

MylarIn general used to refer to polyester film or plastic sheet.

Hard Disks• It contain rigid platters

coated with magnetic oxide• Several platters can be

combined into a disk pack• Disk drive responsible for

reading or writing data from and to the disk

The arm Responsible to move a reading & writing head to desired locationIf the head is touch a platter, it will destroyed the data.

Reading/Writing Data

Every disk contain platters, arms and reading/writing heads

Disk Packs

How Data Is Organized

• Track• Sector• Cluster• Cylinder

Track• The circular portion of the disk surface that passes under the reading/writing head.• The floppy diskette has 80 tracks on each surface.• Hard disk has 1,000 or more tracks on each surface of each platter.

SectorEach track is divided into sectors that hold a fixed number of bytes• Typically 512

bytes per sector

ClusterEvery cluster is contain of two to eight adjacent sectors, depending on the operating system

CylinderThe track on each surface that is beneath the read/write head at a given position of the read/write heads

When file is larger than thecapacity of a single track,operating system will storeit in tracks within the samecylinder

Disk Access Speed• Access time - the time needed to access

data on disk• Three factors• Seek time• Head switching• Rotational delay

• Once data found, next step is data transfer

Seek Time

Time to search the data position on platter

Head switching

The physical head need to reach position on platter.

Rotational DelayDepends on rounds per minute of your Hard Desk Drive ( H.D.D. )• 7200 r/m• 5400 r/m• 1500 r/m

Optical Disk Storage

Compact Disks (CD)• CD-R & CD-RWDigital Versatile Disk (DVD)• DVD-R & DVD-RW & DVD+R &

DVD+RW & DVD+R Dual LayerBlue Ray Disc• BD-R & BD-RE

Magnetic Tape Storage

• Tape similar to tape used in music cassettes

• Used primarily for backup of data stored on disk systems

Organizing and Accessing Stored Data

• Character• Field• Record• File• Database

Accept our thanks

Abdullah HaddadiSaad Aldossari

Abdullah Alshehri

Best Wishes;