Secondary storage Flashcards
Why is secondary storage needed?
For the long-term storage of files and data, as secondary storage is non-volatile
Do embedded systems require secondary storage and why?
No, because they do not need to store data when the power is turned off. The instructions needed to run them are stored in ROM and any user data is held in RAM.
What are the 3 types of secondary storage devices?
Magnetic, optical and solid state
What is an example of a magnetic storage device?
A hard disk drive (HDD)
What are examples of optical storage devices?
CD’s, DVD’s and Blu-ray discs
What are examples of solid state storage devices?
solid state drives and USB memory sticks
What form is data stored in on secondary storage devices?
Binary form
What factors should be considered when thinking of what type of secondary storage device to use?
- Capacity
- Speed
- Portability
- Durability
- Reliability
- Cost
What is the capacity of optical storage?
650Mb to 50Gb
What is the speed of optical storage?
Up to 50mb per second. The speed of optical storage devices is limited because of the presence of moving parts.
How portable is optical storage?
Very portable and ligtweight
How durable is optical storage?
Easily scratched, damaged, or broken. Also, optical storage devices will degrade over time,especially when exposed to sunlight.
How reliable is optical storage?
Quite reliable
How much does optical storage cost
50gb for 45p
What’s the capacity of magnetic storage
Up to 16TB
What’s the speed of magnetic storage?
Up to 200Mb/s. The moving parts mean that magnetic is relatively slow compared to SSD
What’s the portability of magnetic storage?
Internal drives are fixed and so aren’t very portable. Whereas external drives are portable and come in pocket sizes.
How durable is magnetic storage?
Reasonably durable when not in use. However, can be affected by magnetic fields and heat. Also, van be damaged if dropped or knocked.
How reliable is magnetic storage?
Very reliable if looked after e.g. if an HDD hasn’t been dropped several times
How much does magnetic storage cost?
8TB for £120, which is very cheap(cost per byte)
What is the capacity of solid state storage?
Up to 4TB for an SSD, or 256GB for a flash USB memory stick
How fast is solid state?
Up to 3.5GB/s as there are no moving parts
How portable is solid state storage?
Flash drives and memory cards are highly portable. Internal SSD’s aren’t intended to be portable but are very lightweight for use in laptops and tablets.
How durable is solid state?
Extremely durable because of the lack of moving parts
How reliable is solid state storage?
Extremely reliable
How much does solid state storage cost?
4TB for £400
What is the life expectancy of a CD?
10-25 years
Magnetic storage involves the use of….
magnetic fields
Optical devices involve the use of…
lasers
How much power do solid state devices require?
Not much, which makes it ideal for portable devices where a large enough battery life is needed
Which has the greatest storage capacity- optical, magnetic or solid state?
Magnetic
Which is the fastest secondary storage device?
Solid state- due to the lack of moving parts
What is the most durable secondary storage device?
Solid state- due to the lack of moving parts
What’s the most reliable/long lasting secondary storage device?
Solid state
What’s the cheapest secondary storage device?
Magnetic
Is solid state cheap or expensive?
Very expensive
What does DVD stand for?
Digital versatile disk
What are the 3 types of CD’s?
ROM media, Rmedia and RW
DVD’s can store ….X more data than CD’s
10
DVD’s are ….X faster than CD’s
20
Describe ROM media
data is pre-written on ROM media. The data cannot be overwritten. Music, films, software and games are often distributed this way.
Describe R media
R media is blank and data can only be written once, but read many times. Copies of data are usually made using this media
Describe RW
RW works in a similar way to R, except that the disc can be written to more than once.
What are RW CD’s also knows as?
Erasable CD’s
