Mind map
Storage devices and media
Map content
Storage devices and media
Backing storage device
- non-volatile
- data is stored permanently
- slower reading of data
- non-volatile
Types of data access
- Serial access
- data is accessed by starting at the beginning
- access each data in order
- till required information is found
- access each data in order
- used on magnetic tape systems
- data is accessed by starting at the beginning
- Direct access
- used with magnetic disks and optical media (CDs and DVDs)
- key field used is able to calculate where data is stored
- access is much faster
- Serial access
back up data
- able to retrieve data if the original storage device is hacked, lost or destroyed
Types of backing storage media
- Solid State
- data stored as 1s and 0s
- consume much less power
- no moving parts
- Flash drives (memory sticks)
- transport files between computers or back up files
- compact and portable
- cheap to buy
- small: easy to lose
- Flash memory cards
- store photos on digital cameras
- store music files in MP3 players
- compact and robust
- expensive
- lower storage capacity than hard disks
- Magnetic
- Hard disk drives
- Fixed hard disk
- Main backing storsage
- store operating system and working data
- very fast data transfer rate
- very large memory capacities
- can be easily damaged
- not portable
- portable hard disks
- connected to computer via USB
- transfer data, files and software between computers
- large memory capacity
- small and light
- can be easily damaged
- Fixed hard disk
- Magnetic tapees
- data is in serial acces
- robust
- useless in real time
- data transfer rate is fast
- access time is very slow
- Hard disk drives
- Optical
- can be read using light
- CD-ROM and DVD-ROM
- read only memory
- CD: store music files and software DVD: store films
- cheaper
- lower data transfer rate than hard disks
- portable
- store large data files
- CD-R and DVD-R
- recordable once only
- cheaper than RW disks
- once burned,it becomes ROM disks
- if error occurs, disk has to be thrown away
- CD-RW and DVD-RW
- re-writable media
- can be re-used several times
- used to record radio and TV programs
- might accidentally overwrite data
- expensive
- DVD-RAM
- able to watch a recorded program and record a new program at the same time
- have discrete concentric tracks
- use as satellite receivers to allow simultaneous recording and playback
- long life span (min. 30 years)
- writing is very reliable
- expensive
- less compatible
- Blue-ray disks
- large storage capacity
- fast data access and transfer rate
- expensive
- store and play back films
- Solid State