3. Storage Devices and Media

• examples of solid states are

  • USB
  • pendrive
  • memory card
  • memory sticks
• examples of optical disk drives are CD, DVD, Blu-ray, and HD-DVD
• Examples of magnetic storage and media: magnetic tapes, hard drives, floppy disks
• Why do we back up data?

  • To safeguard against loss of data.
• Advantages of magnetic storage:

  • They are generally less expensive than hard disk drives.
  • It is a very robust technology.
  • They have a huge data storage capacity.
  • The data transfer rate is fast.
• Disadvantages of magnetic storage are :

  • Long data access times (uses serial access).
  • When updating, another tape is needed to store the final updated version.
  • They are affected by magnetic fields, a strong field can corrupt data stored on the tape.
• serial access, which means all the previous data needs to be read until the required data is found
• direct access - this means, unlike magnetic tape, earlier data does not have to be read first before the required data is found.
• Advantages of Hard Disk Drive:

  • They have a very fast data transfer rate and fast access times to data.
  • They have a very large memory capacity.
• Disadvantages of Hard Disk Drive:

  • It can be fairly easily damaged.
  • They have many moving parts which affect overall reliability.
  • Their read/write operation can be quite noisy when compared to solid-state drives.
• Videotape, audiotape, and computer data tape are examples of magnetic tape.
• solid state drive is faster, more reliable, and more durable than a hard drive.

  
• Disadvantages of Portable Hard Disk Drives:

  • They can be easily damaged if user accidentally drops it or doesn’t correctly shut down the drive after use.
  • The data transfer rate is not as fast as for fixed hard disk drives.
• Advantages of Portable Hard Disk Drives:

  • Data access time and data transfer rate are very fast.
  • It has a very large memory capacity.
• CD-R/DVD-R

  Uses:

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

  Advantages:

  • Cheaper medium than RW disks.
  • Once burned (and finalized) they behave like a ROM.

  Disadvantages:

  • Can only be recorded once; if an error occurs then the disk has to be thrown away.
  • Not all CD/DVD players can read CD-R/DVD-R.
• CD-RW/DVD-RW

  Uses:

  • Used to record television programs which can be recorded over, time and time again.
  • Used in CCTV systems.
  • Can be used as a backup device for files and data.

  Advantages:

  • Can be written over many times.
  • Can use different file formats each time it is used.
  • Not as wasteful as R format because the files/data can be added later.

  Disadvantages:

  • Can be relatively expensive media.
  • Possible to accidently overwrite data.
• CD-ROM/DVD-ROM

  Uses:

  • These are read-only memory (ROM). Permanent storage method.
  • CD-ROM is used to store music files and to store software
  • DVD-ROM has much larger storage and is used to store films.
  • Used in applications where there is a real need to prevent deletion or overwriting of important data.
• CD-ROM/DVD-ROM

  advantages:

  • They are less expensive than hard disk drive systems.
  • Very portable as they are small and light.
  • Data stored on them is read-only, so it cannot be accidentally overwritten.
• CD-ROM/DVD-ROM

  Disadvantages:

  • Hold far less data than hard disk drives or memory sticks.
  • Very slow data transfer rate and data access times
  • You cannot add your own files to the disks
• The main differences between DVD and Blu-ray are:

  1. Blu-ray uses a blue laser rather than a red laser. (The wavelength of blue light is 405nm, much smaller than the 650nm red laser) This makes pits and lands much smaller so they store five times more data than DVDs.
  2. Blu-ray disks automatically come with a secure encryption system which helps to prevent piracy and copyright infringement.
  3. The data transfer rate for a DVD is 10 Mbps and for a Blu-ray disc, it is 36 Mbps.
• Blu-Ray discs

  Uses:

  • Home video consoles.
  • Storing and playing back movies.
  • Computers can use this technology for data storage or backing hard drives.
  • Camcorders can use this media to store movies.
• Blu-Ray discs

  Disadvantages:

  • Relatively expensive discs.
  • encryption problems when used to store videos.
  • The introduction of HD (high definition) DVD players has reduced the advantages of using Blu-ray technology.
• Blu-Ray discs

  Advantages:

  • Very large storage capacity.
  • Very fast data transfer rate.
  • The data access speed is also greater than with other optical media.
  • Blu-ray discs automatically come with a secure encryption system.
• Solid-state drives (SSD)

  Disadvantages:

  • SSD endurance - SSDs are conservatively rated at only 20GB write operations per day over a three-year period.
  • More expensive than magnetic hard disks.
  • Smaller storage capacity than magnetic hard disks.
• Solid-state drives (SSD)

  Advantages:

  • They are more reliable as they have no moving parts.
  • They are considerably lighter, and suitable for laptops.
  • They do not have to ‘get up to speed’ before they work correctly.
  • They have lower power consumption.
  • They run much cooler than HDDs.
  • Because of no moving parts, they are very thin.
  • SSD data access time is only 0.1 milliseconds compared to 10 milliseconds for HDD.
  • Data transfer speed for SSDs is also much faster than for HDDs.
• Pen drives (Memory sticks)

  Uses:

  • Transporting files between computers or using as a backing store.
  • Used as a security device to prevent software piracy (known as a dongle).
• Pen drives (Memory sticks)

  Disadvantages:

  • Cannot write protect the data/files by making it ‘read-only’.
  • Easy to lose (due to the small physical size).
  • The user needs to be very careful when removing a memory stick from a computer - incorrect removal will corrupt the data on the memory stick and make it useless.
• Pen drives (Memory sticks)

  Advantages:

  • Very compact and portable media.
  • Very robust.
  • Does not need additional software to work on most computers.
  • They are not affected by magnetic fields.
• Flash Memory cards

  Uses:

  • Storing photos on digital cameras.
  • Used as mobile phone memory cards
• Flash Memory cards

  Disadvantages:

  • Expensive per gigabyte of memory when compared to HDDs.
  • Have a lower storage capacity than hard disks.
  • Have a finite life regarding the number of times they can be read from or written to.
  • Memory cards are the smallest storage devices available, making them more likely to be lost, stolen or damaged.
  • Users must often purchase a card reader or USB converter to view the data.
• Flash Memory cards

  Advantages:

  • Very compact.
  • Because of no moving parts, they are very durable.
  • They can hold large amounts of data.
  • Compact cameras and smartphones can read and write memory cards, allowing the user to transport extensive collections of photographs, songs etc.