1. 3. Storage devices and media By: me

2. 3.1.1 what is backing up of data? 3.1.2 why back up data? WHAT?  Refers to the copying of files/data to a different medium in case of a problem with the main secondary storage deivce WHY?  To safehuard against loss of data due to failure of the original secondary storage device  To safeguard against damage from hackers  Made in case the files need to be used elsewhere

3. Car 1Red1.5 litersPetrol3 doorsnew Car 2Blue1.3 litersPetrol5 doorsUsed Car 3Green2.2 litersDiesel5 doorsUsed Car 4White1.6 litersPetrol2 doorsNew field 12 3 45 6 1 2 3 4 record FIELD + RECORD =FILE 3.2 types of access

4. 3.2.1 Serial access  Start at the beginning of the file and then access in turn until the required record is found.  Primarily used on magnetic tape system  Slow form of data access

5. 3.2.1 Serial access  When the original magnetic tape (masterfile) needs updating, an additional tape (transaction file) is required.  The transaction file contains all the new data that the master file needs to be updated with New data to be used to update master file Old data stored on magnetic tape New tape produced from A and B A B

6. 3.2.2 Direct access  Used with magnetic disks, optical media and solid state media.  Computer uses the key field to calculate where data should be stored.  Much faster than with serial access  Used in vital data access speed such as booking air tickets or automatic stock control

7. 3.3 secondary storage media  All systems of the personal computer are equipped with some form of secondary storage.  BYTE is used to measure the size of memory or storage. Storage sizeNumber of bytesNumber of bytes as power of 10 1KB1000 bytes10 3 bytes 1MB1 000 000 bytes10 6 bytes 1GB1 000 000 000 bytes10 9 bytes 1TB1 000 000 000 000 bytes10 12 bytes

8. 3.3 Storage device  3 types of storage media: -magnetic -optical -solid state

9. 3.3.1 Magnetic storage media  Depend on the magnetic properties of certain materials  Coated on the surface of a disk or tape.  Many hard disk drive are made up of more than one disk. These disks are called platters  Each platter is made from glass, ceramic or aluminum coated in nickel alloy that can be magnetized.  In the case of tape, plastic that is coated in a magnetic material is used to store the data

10. Fixed/internal hard disk drive (HDD)  Store operating systems, systems software and working data/files.  Storing applications software that needs fast retrieval and storage of data  Used in real time systems (robots….)  Used in file servers for computer networks

11. Fixed/internal hard disk drive (HDD) advantages  They have a very fast data transfer rate and fast access times to data  They have a very large memory capacities

12. Fixed/internal hard disk drive (HDD) disadvantages  Can be easily damaged if not correctly shut down  They have many moving parts when compared to SSDs  Their read/write operation can be quite noisy compared to SSDs

13. Portable hard disk drives  Can be used as backup systems to prevent loss of data  Used to transfer data/files/software between computers.

14. Portable hard disk drives advantages  The data access time and data transfer rate is very fast  They have large memory capacity  They can be used as a method of transferring information between computers.

15. Portable hard disk drives disadvantages  They can be easily damaged if dropped or subjected to a strong magnetic field

16. Magnetic tapes  In applications where batch processing is used  Used as backup media since all data needs to be stored  Used in long-term archiving of data; magnetic tapes have huge data storage

17. Magnetic tapes advantages  Generally less expensive  It is a very robust technology  They have huge data storage capacity  The data transfer rate is actually fast

18. Magnetic tapes disadvantages  Very slow data access time  When updating, another tape is need to store the final updated version  Affected by magnetic fields

19. 3.3.2 OPTICAL STORAGE MEDIA

20. CD/DVD disks  Laser light is used to read data and to write data on the surface of the disk.  The data is stored in pits and bumps on the spiral track.  Can be designated as follows:  R- write once only  ROM- can only be read  RW – can be written to or read from many times

21. CD-ROM and DVD-ROM  CD-ROM Store music files, software, computer games and reference software  DVD-ROM have much larger storage and are used to store films  CD-ROMs and DVD-ROM are used in applications where there is a real need to prevent the deletion or overwriting of important data.

22. CD-ROM and DVD-ROM advantages  They hold far more data than floppy disks  They are less expensive than HDD systems

23. CD-ROM and DVD-ROM disadvantages  The data transfer rate/data access time is slower than for hard disks.

24. CD-R and DVD-R  Home recordings of music (CD-R) and films (DVD-R)  Used to store data to be kept for later use or to be transferred to another computer.

25. CD-R and DVD-R advantages  Cheaper than RW disks  Once burned they are like a ROM

26. CD-R and DVD-R disadvantages  If finalized, CD-R/DVD-R can only be recorded on once  Not all CD/DVD players can CD-R/DVD-R

27. CD-RW and DVD-RW  Used to record television programs  Not as wasteful as R format as more files/ data can be added to at a later stage  Used in CCTV systems

28. CD-RW and DVD-RW advantages  Can be written over many times  Can use different file formats each time it is used

29. CD-RW and DVD-RW disadvantages  Can be relatively expensive  It is possible to accidentally overwrite data

30. DVD-RAM  Used in recording devices  Used in camcorders

31. DVD-RAM advantages  Have long life  Possible to do a rewrite operation over 100 000 times  Writing on DVD-RAMs is very reliable  Very fast access  No need to finalize  Large capacity  Offer the ability to read data the same time as data being written

32. DVD-RAM disadvantages  Not as compatible as R or RW format  Relatively expensive  Have been superseded by newer technologies

33. BLU-RAY DISCS DIFFERENCES WITH DVDs  A blue laser, rather than red, is used to carry out read and write operations  Using blue laser light means pits and bumps can be much smaller  Uses a singal 1.1mm-thick polycarbonate disk  Using two sandwiched layers can cause birefringence  Blue-ray discs automatically come with a secure encryption system

34. BLU-RAY DISCS  Used in home video consoles  Storing and playing back movies  PCs can use this tech for data storage or backing up hard drives  Camcorders can use this media to store movie footage

35. BLU-RAY DISCS advantages  Very large storage capacity, therefore ideal for storing high-def movies  Very fast data transfer  Data access speed is l=also greater than with other optical media  Blu-ray discs automatically come with a secure encryption system

36. BLU-RAY DISCS disadvantages  Relatively expensive  Encryption problems  Fewer movie titles on Blu-ray format, which is reducing its impact on the home movie market

37. SSD  Taking over HDDs  Include: memory sticks/pen drives, flash memory cards