Storage Devices

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Optical storage devices

•With proper care, optical media can last a long time.•When data is written to them, they cannot be reused. This is excellent for archiving because data is preserved permanently of being overwritten. •Optical media are widely used on other platforms, including the PC. •Optical media provide the capability to pinpoint a particular piece of data stored on it, independent of the other data on the volume .

•The write-once read-many (WORM) ,it excellent for archiving, but it also prevents you from being able to use that media again. •The server uses software compression to write compressed data to your optical media. It need the long time to stroe more datas.

Advantages : Disadvantages :

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CD-Rom

Advantages :• Data cannot Be erased –

you cannot lose your data• Easy to carry around• Cheap to produce• Can Be read By a DVD

drive

Disadvantages :• Fragile • Can scratch easily – this

effects the data when the laser reads it

• Slower to access than a hard drive

Typical size = 650mb

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DVD-ROM

Read Only Memory (Read Only)Advantages :

•Can only be used for reading.•Movies you buy or rent are usually DVD-ROM.•Although some discs can hold up to 17 GB of information.•Can hold a minimum of 4.7 GB of movies, music, text, or images.•Access rates for DVD ROMs range from 600 Kbps to 1.3 Mbps.

Disadvantages :•Once the information is recorded onto a DVD ROM, it can’t be changed or altered.

•You may have trouble operating some programs with your DVD ROM drive.

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CD R/DVD RAdvantages : Disadvantages :

Recordable (Only write one time)

•Can only be written with -R type drives. •Can be read with -R or +R type drives. •DVD+R •2 hours of video in SP mode or 4 hours in EP mode •Can only be written with +R type drives. •Can be read with -R or +R type drives.

DVD recordable

•Data on a DVD-R cannot be changed

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CD RW/DVD RWDVD-rewritableCompact Disc Re-Writable

Advantages : Disadvantages :•The data burned on a CD-RW cannot be changed

•you have to completely erase a CD-RW every time you want to change the files or add new data

•they don't store data reliably for as long as CD-Rs do.

•A CD-RW can be written to multiple times.

•CD-RWs a good choice for making frequent backups.

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DVD RAMDVD- Random Access Memory

•Long life—  without physical damage

•Can be rewritten over 100,000 times

•Disc defect management designed to safeguard data.

•DVD-burning software may not be required 

Advantages : Disadvantages :

•Less compatibility than DVD+RW and DVD-RW

•12x media is not reportedly available in Europe.

•DVD-RAM media have always been more expensive than other types of DVD.

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HD DVD

High-Definition/Density DVD

Advantages : Disadvantages :•high-density optical disc format for storing data

•HD DVD was envisaged to be the successor to the standard DVD format.

•maximum capacity: 15 GB per layer

•it’s hard to deny that the HD-DVD player is a great device for the price

•It’s expensive

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Blu-rayis an optical disc storage medium designed to supersede the standard DVD format.

•It’s main uses are for storing high-definition video, PlayStation 3 video games.

•25 GB per single layered, and 50 GB per dual layered disc

•a standard DVD uses a 650 nanometer red laser, Blu-ray uses a shorter wavelength

•six times more data storage than a DVD

Advantages : Disadvantages :

•It’s too expensive.

•Blu-ray attempted to woo consumers with awfully big pockets by presenting them

•Blu-ray disc can't hold much more than four or five hours of high definition content.

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Solid state backing storage

Disadvantages :•Smallest form of

memory

•More expensive thanother forms but can be easily written to and updated.

•used as removable storage

More robust than other forms of storage.

Advantages :

Memory sticksPen drives

Advantages : Disadvantages :•Can store up to many Gb.

•Used to transport files and backupdata from computer to computer.

• It can be lost.

•It can be broken, if we dropped.

•It can lost the information easily.

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Flash memory cards

•Used in digital cameras, palmtops, mobile phones, MP3players.

Advantages : Disadvantages :

•It can be lost and broken