Magnetic Storage
Computer Science: Cambridge International GCSE, topic 1.3.11
How Magnetic Storage Works
The most common type of magnetic storage is the Hard Disk Drive (HDD).
Storing a bit
- The value of each bit of data (0 or 1) is represented as a positively or negatively charged magnetic particle.
- These particles are part of a magnetic disk called the platter.
Accessing data
- Data could be stored anywhere on the disk, and so to read/write data we first need to find the location on the disk.
- A magnetic read/write head is used to access the data while the platter spins.
Reliability
- The HDD has moving parts.
- Although the HDD is generally reliable, any device with moving parts will be subject to wear-and-tear.
- HDDs can also be damaged by shocks. They are not robust.
Properties of Magnetic Media
To compare magnetic storage with the other types of media, it is important to understand the advantages and disadvantages of storing data magnetically.
Low cost
- Magnetic media is very low cost per unit capacity.
- This makes it an economical choice for storing large amounts of data.
Low speed
- Magnetic media needs a high number of moving parts.
- The high number of moving parts make magnetic media slow to access.
Good reliability
- Magnetic media is reliable and tends to last for a long time.
- Magnetic media is not robust, and tends to break on impact or during vibrations.
High capacity
- Magnetic media can store a large quantity of data in a compact way.
- This makes them a popular choice for archives as well as home computers.
Test yourself on Magnetic Storage
Which of the following are true of Hard Disk Drives?
Why are Hard Disk Drives subject to wear-and-tear?
Why might a company choose to use magnetic media to make backups of large files?
Why might a company choose to use a different type of storage device if they need to have fast access to their data in the future?