2.2: Secondary Storage
Exam Board:
OCR
Specification:
J277
Secondary storageis non-volatile storage used to save and store data that can be accessed repeatedly.
Secondary storage is not directly embedded on the motherboard (and possibly evenexternal) and therefore further away from the CPU so it is slower to access then primary storage.
Storage Characteristics you should know:
CAPACITY: The maximum amount of data that can be stored on the device.
DURABILITY: The strength of the device, to last without breaking.
PORTABILITY: How easy it is to carry the device around.
ACCESS SPEED: How quickly data on the device can be read or edited.
COST: The average price it costs to purchase the storage device.
RELIABILITY: The likelihood of the device continuing to perform well over time.
Magnetic Storage
A magnetic hard disk drive (HDD) is the most common form of secondary storagewithin desktop computers. A read/write head moves nanometres above the disk platter and uses the magnetic field of the platter to read or edit data.
An obsolete (no longer used) typeof magnetic storage is a floppy disk but these have been replaced by solid state devices such as USB sticks which are much faster and have a much higher capacity.
Another type of magnetic storage that is still used is magnetic tape. Magnetic tape has a high storage capacity but data has to be accessedin order (serial access) so it is generally only used by companies tobackup or archivelarge amounts of data.
Magnetic Storage Characteristics (Hard Disk Drive):
✓ -Large CAPACITYand cheaper COST per gigabyte than solid state.
✓-Modern external HDDs are smallandwell protected so they are DURABLEand PORTABLE, however because of the moving parts, they should not be moved when powered on because it can damage the device.
X-Slower ACCESS SPEEDthan solid state butfaster than optical storage.
Optical Storage
Optical storage uses a laserto projectbeams of light onto a spinning disc, allowing it to read data from a CD, DVD or Blu-Ray.
This makes optical storage the slowest of the four types of secondary storage.
Disc drives are traditionally internal but external disc drives can be bought for devices like laptops.
Magnetic Disks are spelled with a k and Optical Discs have a c.
Optical Storage Characteristics:
X-LowCAPACITY: 700 MB (CD), 4.7 GB (DVD), 25 GB (Blu-ray).
X- Not DURABLEbecausediscs are very fragile and can break or scratcheasily.
✓-Discs are thin andvery PORTABLE. Also very cheap to buy in bulk.
X-Optical discs have theSlowest ACCESS SPEED.
Solid State Storage
There are no moving parts in solid state storage.
SSDs (Solid State Drives) are replacing magnetic HDDs (Hard DIsk Drives) in modern computers and video game consoles because they are generally quieter, faster and useless power.
A USB flash drive (USB stick)is another type of solid state storage that is used to transport files easily because of its small size.
Memory cards, like the SD card in a digital camera or a Micro SD card in a smartphone, are another example of solid state storage.
Solid State Characteristics:
X - More expensive COST per gigabytethan magnetic.
✓ -Usually DURABLEbut cheap USB sticks can snap or break.
✓ -The small size of USB sticks and memory cards mean they are very PORTABLE and can fit easily in a bag or pocket.
✓ -Solid State storage have ahigh CAPACITYand the fastest ACCESS SPEED because they containno moving parts.
Questo's Questions
2.2 - Secondary Storage:
1.Rankmagnetic, optical and solid-state storage in terms of capacity, durability, portability,speed and cost. For example, magnetic has the highest capacity, then solid-state, then optical. This could be completed in a table. [15]
2. Justify which secondary storage should be used in each scenario and why it is the most appropriate:
a. Sending videos and pictures to family in Australia through the post. [2]
b. Storing a presentation to take into school. [2]
c. Storing project files with other members of a group to work on together. [2]
d. Backing up an old computer with thousands of files to a storage device. [2]
