1.4 backing storage_media_n_devices

Backing Storage Media and DevicesAll computer systems require some form of backing storage to store data permanently for further processing.

Magnetic

Optical

Solid State

Storage Devices

Categories of Storage Devices

Magnetic Media

Magnetic tapes Uses1. In batch-processing

situations, for example updating banking accounts with cheques.

2. In utility billing systems3. Payroll applications4. Making backups of data

Advantages Disadvantages

1. Cheaper bit for bits than using disks.

1. Access is slow, so uses are limited.

2. Very robust as they are encased in a cartridge.

2. Updating files requires a new tape to be created.

3. Easier to remove and keep away from computer.

4. Data transfer rate is fast.

Fixed Hard Disks UsesFixed hard disks are essential in any system that requires fast data access times and fast data transfer rates:1. Used in real-time system such as

robotics, rocket launching, etc.2. Essential in any online system3. Used in file servers in computer

networks

Advantages Disadvantages

1. Data transfer rate is fast.

1. They are easily damaged.

2. Data access times are fast.

3. Have a very large capacity.

Portable Hard Disks Uses1. used as backup media and for

transferring large files from one location to another.

2. transferring server software from one network to another.

Advantages Disadvantages

1. Data transfer rate is fast.

1. They are easily damaged.

2. Data access times are fast.

2. transfer rates are not as fast as fixed hard disks

3. Have a very large capacity.

3. More expensive than other forms of removable media such as CDs or DVDs

Optical Storage Backing Media

CD ROMs / DVD ROMs Uses1. CD ROMs are used to store music

albums and to provide audio output in home entertainment systems.

2. DVD ROMs are mainly used for storing films, now are increasingly being used for data storage.

Advantages Disadvantages1. DVDs hold more data than CDs.

1. Data transfer rates for CDs and DVDs are slower than hard disks.

2. CDs are cheaper than DVDs.

2. data access times are longer than for hard disks.

3. Both hold more data than a floppy disk.

4. Both are cheaper than hard disks.

5. Both are more robust than hard disks.

CD RWs / DVD RWs Uses1. used for recording television

programs that can be replaced later

2. used in latest handy cams/video cameras

Advantages Disadvantages

1. Can be used more than once

1. Their costs make them impractical for use as permanent back up media.

2. Different versions of files can be over written, thereby virtually increasing capacity.

2. Files can be overwritten accidently.

CD Rs / DVD Rs Uses1. used for home recordings of

music on CD and films on DVD2. used for storing and transferring

data from one machine to another

Advantages Disadvantages

1. Cheaper than CD/DVD RWs 1. Can only be recorded on once

2. once burnt, they cannot be accidently written over.

2. if several versions are recorded on the disk, takes up more space than storing on CD/DVD RWs.3. not all CD players will read CD Rs.

DVD RAMs Uses1. DVD-RAMs are used for general

data storage2. used for data archiving, as it lasts

longer than other optical media3. in some camcorders, they are

used for recording video

Advantages Disadvantages

1. have a great capacity than CDs/DVDs.

1. not compatible with most DVD players.

2. more durable than DVDs.

2. more expensive than other types of DVD media.

Blu-Ray Disks Uses1. Mainly used in home video game

consoles.2. Devices have been developed to

facilitate the playing and recording of videos.

3. PCs and laptops are being developed that use blu-ray disk drives for data storage as well as playing videos.

4. They are mainly used in many camcorders.

Advantages Disadvantages

1. Store more than other optical media.

1. Very expensive compared with other data storage media.

2. Data transfer rates are high.

2. Problems are being faced with the encryption techniques used to prevent piracy.

3. Access speeds are higher with blu-ray players than with other optical devices.

Minidisks Uses1. Mainly used in music players and

data storage.

Advantages Disadvantages

1. Can be rewritten more times than other media.

1. Have slower transfer rates than other disks.

2. More robust than other optical media.

2. Store less data than other music players.

3. More expensive than other portable players.

Solid State Backing Storage

Memory Sticks / Pen drives Uses1. Used to transport files and

backup data from computer to computer.

2. Used by system and network administrators for carrying software fixes.

Advantages Disadvantages

1. More compact than equivalent optical or magnetic media.

1. More expensive per Gbyte than hard disk drives.

2. More robust – can even survive “washing”.

2. Drives cannot be write protected.

3. Do not need software drivers to operate.

Flash memory cards Uses1. Used for storing photographs in

digital cameras.2. Used in mobile phones to store

phone numbers, photographs, etc.

3. Used in MP3 players to store music.

4. Used as backing storage in many handheld computers.

Advantages Disadvantages

1. More compact than equivalent optical or magnetic media.

1. More expensive per Gbyte than hard disk drives.2. Have limited number of read/write operations.

3. Have lower storage capacity than hard disk drives.