Secondary Storage Flashcards Preview

Paper 2 - Computer Science > Secondary Storage > Flashcards

Flashcards in Secondary Storage Deck (14)
Loading flashcards...

What type of data is Secondary Storage?

Non-Volatile, Data is not lost when there is no power


What does secondary storage allow for?

Storing a backup copy of data, so that if lost data can be restored


What does a Hard disk drive work?

- Consists of metal disks which are coated with a magnetic material
- The disks are divided into tracks which are divided into sectors
- The disks rotate very quickly
- Read/write heads move across the disk surface to access or store data on the disk


Why are HDD's known as a magnetic storage device?

Because the data is stored in magnetic material


Advantages of using a Hard Disk Drive?

- They have a high data transfer rate
- Highest storage capacity


Disadvantages of using a Hard Disk Drive?

- Not very portable, care has to be taken handling them
- Access times are slower than SSD's because they have moving parts


How do optical storage devices work?

- Has a plastic disk with a mirrored surface
- Data is burned or pressed onto the surface of the disk
- This creates a series of Pits and Lands
- The pits has a value of zero, the lands have a value of one
- Laser beams are used to read the data on the disk since the pits and lands reflect different amounts of light, which are decoded into the original binary data.
- The reader starts reading data on the inside of the disk and works its way to the outside.


What are the different types of Optical storage and their storage capacity?

- CD - 650 Mb
- DVD - 4.7 Gb
- Blu-ray - 25 Gb


Advantages of using Optical Storage?

- Very portable
- Cheap to produce


Disadvantages of using Optical Storage?

- Can be easily damaged
- less storage capacity than a hard disk drive
- Slower access time that Hard Disks and Solid state drives


How do Solid State Drives work?

-comprised of NAND flash memory cells arranged in a grid
-has a controller that manages pages/blocks of memory
- data is stored using floating gate transistors
-The transistors can trap and store charge
-data must be read in pages and written/erased in blocks


Advantages of using Solid State Drives ?

-They can read, write and access data faster that Hard drives as they have no moving parts
-They are more durable than optical storage/HDD's


Disadvantages of using Solid State Drives ?

- More expensive to buy than Hard Disk Drives
- Tend to be of smaller capacity that Hard Disk Drives


Without increasing the overall size how can the capacity of a HDD be increased?

-By adding more platters
-By decreasing the track width