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What are the types of Storage Media?
Magnetic Storage Media, Optical Storage Media and Solid State Storage Media.
What are the Magnetic Storage Media Devices?
Fixed and Portable Hard Disk Drives
Magnetic Tape Drives and Tapes
How does Hard Disk Drives works?
The data is stored in on concentric circles on the surfaces known as tracks and sections within each track are called sectors.
When the data file is stored on a disk it may be split up and saved on different sectors and track.
The operating system creates an entry in the disk’s file allocation table (FAT) for the new file that records where each part is located and their sequential order
What are the advantages of hard disk drives?
They can store very large amounts of data
They can access the data randomly without having to start at the beginning and search through everything. It has FAT showing where everything is stored. This type of access is called direct access or random access
Very low cost
What are the disadvantages of hard disk drives?
The are susceptible to physical knocks that might cause the read/write head to hit the disk and corrupt data
They are slower to read and write data than solid state drives
They can be noisy
What are fixed hard disk drives?
Fixed hard disk drives are permanently connected to the computer and are contained within the cases of both desktop and laptop computers. They are built in.
What are Portable hard disk drives?
Portable hard disk drives are contained within their own cases and are separate from main computer systems to which they are connected by cable.
What are the advantages of portable hard disk drives?
It is compact enough to bring with you when you're on the go, and some of them, despite being fairly thin - have a sturdy outer shell to assist reduce potential damage.
It can be easily used by multiple PCs of the same operating system for file sharing, particularly for large files.
It allows scheduled automatic backup files, which is easy to set up; then it won’t matter if you forget to backup.
It allows for quick archiving of data
What are the disadvantages of portable hard disk drives?
They could be damaged as they are being moved
They are insecure, as they could get lost or stolen with the consequent loss of data
The data transfer rate is not as fast as for fixed hard disk drives
How does Magnetic Storage Media work?
Holds data magnetically.
The surface area of the media is magnetised so that it can hold bits of data.
The device that reads media can also read the bits held on the surface area
How does Optical Media and Optical Storage Devices work?
Holds data by burning ‘dots’ onto the surface with a high-powered laser.
The data that reads the media can read the data by shining a lower-powered laser over the dots.
What are the Optical Media and Optical Storage devices?
CD-RW/ DVD-RW
CD-ROM/ DVD ROM
Blu-Ray Discs
What are the uses of CD-R/DVD-R?
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.
What are the advantages of CD-R/DVD-R?
Cheaper medium than RW disks.
Once burned (and finalised), they behave like a ROM.
What are the disadvantages of CD-R/DVD-R?
It 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.
What are the uses of CD-RW/DVD-RW?
Used to record television programs which can be recorded over, time and time again.
Used in CCTV systems.
It can be used as a backup device for files and data.
What are the advantages of CD-RW/DVD-RW?
It can be written over many times.
You can use different file formats each time it is used.
It is not as wasteful as the R format because the files/data can be added later.
What are the disadvantages of CD-RW/DVD-RW?
It can be relatively expensive media.
Possible to accidentally overwrite data.
What are the uses of CD-ROM/DVD-ROM?
These are read-only memory (ROM), which means they can’t be written over and can only be read. Permanent storage method.
CD-ROM is used to store music files and to store software, computer games and reference 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.
What are the advantages of CD-ROM/DVD-ROM?
They are less expensive than hard disk drive systems.
They are very portable as they are small and light.
Data stored on them is read-only, so it cannot be accidentally overwritten.
What are the disadvantages of CD-ROM/DVD-ROM?
Hold far less data than hard disk drives or memory sticks.
Very slow data transfer rate and data access times, as compared to hard disk drives.
You cannot add your own files to the disks because they are both read-only.
What are the main differences between DVD and Blu Ray?
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.
Blu-ray disks automatically come with a secure encryption system, which helps to prevent piracy and copyright infringement.
The data transfer rate for a DVD is 10 Mbps, and for a Blu-ray disc, it is 36 Mbps.
What are the uses of Blu-Ray Discs?
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.
What are the advantages of Blu-Ray Discs?
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.
What are the disadvantages of Blu-Ray Discs?
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.
What does Solid State Backing Storage do?
Holds data on devices that don’t have any moving devices.
What are the devices of Solid State Drives?
Pen Drives (Memory Sticks)
Flash Memory Sticks
What are the uses of Solid-state drives (SSD)?
storage device to store files, applications, OSs, and so on.
What are the advantages of Solid-state drives (SSD)?
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.
What are the disadvantages of Solid-state drives (SSD)?
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.
What are the uses of Pen drives (Memory sticks)?
Transporting files between computers or using as a backing store.
Used as a security device to prevent software piracy (known as a dongle).
What are the advantages of Pen drives (Memory sticks)?
Very compact and portable media.
Very robust.
Does not need additional software to work on most computers.
They are not affected by magnetic fields.
What are the disadvantages of Pen drives (Memory sticks)?
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.
What are the uses of Flash Memory cards?
Storing photos on digital cameras.
Used as mobile phone memory cards.
Used in MP3 players to store music files.
Used as a backing store in hand-held computer devices.
What are the advantages of Flash Memory cards?
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.
What are the disadvantages of Flash Memory cards?
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, specifically the micro SD card, 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.
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