Secondary storage provides non-volatile, permanent data storage. Unlike RAM, data is retained when power is off. It stores files, programs, the OS, and all user data.
Types of Secondary Storage
1. HDD (Hard Disk Drive)
Uses magnetic platters and a read/write head
Advantages: large capacity (1–20 TB), cheap per GB
Disadvantages: slower than SSD, moving parts = fragile, produces heat/noise
2. SSD (Solid State Drive)
Uses flash memory (no moving parts)
Advantages: very fast, silent, durable, lightweight
Disadvantages: more expensive per GB than HDD
3. Optical Discs (CD, DVD, Blu-ray)
Uses a laser to read/write on a disc
Advantages: cheap to produce, portable, works on most devices
Exam tip: Edexcel questions often ask you to "Compare HDD and SSD" or "Justify the most suitable storage for a scenario." Always link the feature to the use case: e.g. "An SSD is suitable because it has no moving parts, making it more durable for use in a laptop that is often moved."
⚠️ Common Mistakes
Saying HDD uses flash — HDD uses magnetic platters; SSDs and USB drives use flash
Confusing volatile RAM and non-volatile secondary storage
Forgetting that optical discs use lasers
Not justifying storage choice — always explain WHY a type suits the scenario
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Worksheet — 3.2a Secondary Storage
8 Edexcel-style questions · instantly marked
Q1State two advantages of an SSD over an HDD.[2]
✅ Mark scheme
Any two: faster access speed [1]; no moving parts so more durable/reliable [1]; silent operation [1]; lighter weight [1].
Q2What technology does an HDD use to store data?[1]
✅ Mark scheme
Magnetic storage [1] — uses magnetised platters and a read/write head.
Q3A student needs portable storage to carry files between school and home. Which type of secondary storage is most suitable? Justify your answer.[2]
✅ Mark scheme
USB flash drive [1]; because it is small, portable, and plug-and-play with no power needed [1].
Q4State one disadvantage of optical discs compared to SSDs.[1]
✅ Mark scheme
Any one: lower capacity [1]; slower access [1]; can be scratched/damaged easily [1].
Q5What is the main disadvantage of SSDs compared to HDDs?[1]
✅ Mark scheme
SSDs are more expensive per gigabyte than HDDs [1].
Q6Why is secondary storage non-volatile, while RAM is volatile?[2]
✅ Mark scheme
Secondary storage retains data without power because it uses magnetic or flash technology that doesn't require power to maintain state [1]; RAM is volatile because it uses electrical capacitors that lose charge when power is removed [1].
Q7A hospital needs to store large medical imaging files (MRI scans) at low cost. Which storage would you recommend? Justify.[2]
✅ Mark scheme
HDD [1]; because HDDs offer very large capacity at a low cost per GB, suitable for storing many large image files [1].
Q8What technology do optical discs use to read and write data?[1]
✅ Mark scheme
Optical discs use a laser to read and write data [1].
Topic Quiz
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Mini Test — Secondary Storage
Timed exam-style test.
⏱10:00
Section A — Multiple Choice [5 marks]
Q1An HDD stores data using:[1]
Q2Which storage is fastest?[1]
Q3SSD stands for:[1]
Q4A Blu-ray disc can store approximately:[1]
Q5The main advantage of HDD over SSD is:[1]
Section B — Short Answer
Q6Compare HDD and SSD. Include technology used, speed, cost, and durability.[3]
Mark schemeHDD uses magnetic platters, SSD uses flash memory [1]; SSD is faster [1]; HDD is cheaper per GB [1]; SSD is more durable (no moving parts) [1].
Q7A filmmaker needs to store 10 TB of high-resolution video footage cheaply. Recommend a storage type and justify.[2]
Mark schemeHDD [1]; because HDDs offer the largest capacities (up to 20 TB) at the lowest cost per GB, making them suitable for large file collections [1].