Secondary Storage
Secondary storage is non-volatile storage, such as hard disk drives, solid-state drives and optical discs, that holds data and programs permanently even when the power is off. It complements RAM in the memory hierarchy and is assessed in Paper 1 of GCSE Computer Science alongside memory and system software.
Method
- Learn the three main storage technologies: magnetic, optical and solid-state, and one example device of each.
- Learn the typical capacities and common uses of CDs, DVDs and Blu-ray discs.
- Compare hard disk drives and solid-state drives: how each stores data, and the advantages and disadvantages of each in terms of speed, durability, cost and moving parts.
- Learn common uses of magnetic tape for backups, and why it suits archiving large amounts of data cheaply.
- Practise capacity and data-rate calculations, converting between units such as MB, GB and TB.
- Practise choosing and justifying a suitable storage type for a given scenario, referring to capacity, speed, durability, portability and cost.
Worked example
A student's tablet has 32 GB of free storage space. Each song file is on average 5 MB in size. Calculate the maximum number of songs that can be stored in the free space.
- Convert 32 GB to MB: 32 x 1000 = 32000 MB.
- Divide the total free space by the size of one song: 32000 / 5.
- Calculate: 32000 / 5 = 6400.
- Final answer: 6400 songs.
Practice questions
Try each question, then tap to reveal the answer.
Exam-style questions
Written in the style of a GCSE Computer Science exam paper, with a full mark scheme.
Explain, referring to platters and a read/write head, how a magnetic hard disk drive (HDD) stores data.
A block of flats installs a security camera system in its car park that records continuously and automatically overwrites its oldest footage once the storage is full. Recommend a suitable type of secondary storage for the camera system's recorder, justifying your answer by referring to at least two characteristics of storage.
A media production company is buying new workstations that will mainly be used to edit large, high-resolution 4K video files. Discuss how suitable magnetic, optical and solid-state storage would each be for this purpose, and recommend, with justification, which type of storage the company should use.
Free printable worksheet
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