Knowledge Organiser: Secondary Storage
Part of Secondary Storage · GCSE GCSE Computer Science revision
This topic summary covers Knowledge Organiser: Secondary Storage within Secondary Storage for GCSE Computer Science. Revise Secondary Storage in Memory & Storage for GCSE Computer Science with 15 exam-style questions and 18 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 11 of 11 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 11 of 11
Practice
15 questions
Recall
18 flashcards
Knowledge Organiser: Secondary Storage
Key Terms
- Secondary storage: Non-volatile storage that retains data when power is off (e.g. HDD, SSD, optical)
- HDD: Hard Disk Drive — magnetic storage using spinning platters and a read/write head
- SSD: Solid State Drive — flash memory storage with no moving parts
- Optical storage: Uses a laser to read/write data on discs (CD, DVD, Blu-ray)
- Non-volatile: Data is retained when power is switched off
- Volatile: Data is lost when power is switched off (e.g. RAM)
Must-Know Facts
- Speed ranking: SSD (fastest, 500–7000 MB/s) > HDD (100–200 MB/s) > Optical (1–8 MB/s)
- Cost per GB: HDD cheapest > Optical > SSD most expensive
- Capacity: HDD highest (1–20 TB) > SSD (256 GB–4 TB) > Optical (700 MB–100 GB)
- SSD is more durable than HDD because it has no moving parts
- HDD uses spinning magnetic platters — vulnerable to physical shock
- Optical storage is highly portable and needs no power to retain data
- Secondary storage is needed because RAM is volatile — data would be lost on shutdown
Key Concepts
- Choose SSD: speed-critical tasks (OS, games, video editing)
- Choose HDD: bulk storage, photo archives, backups (cheap per GB, high capacity)
- Choose Optical: distributing software/media, portable archives
- Many modern computers use SSD + HDD together: SSD for speed, HDD for capacity
Common Mistakes
- Confusing secondary storage with RAM: RAM is primary memory (volatile, temporary); secondary storage is non-volatile and permanently keeps data when the power is off
- Saying SSDs have moving parts: SSDs use flash memory chips with no moving parts — it is HDDs that use spinning magnetic platters and a moving read/write head
- Choosing the wrong storage for a given scenario: Always justify your choice — speed (SSD), cost per GB (HDD), portability (optical/flash), durability (SSD) are the key factors examiners expect
- Saying optical discs are faster than HDDs: Optical drives (CD/DVD) are significantly slower than both HDDs and SSDs — they are chosen for distribution and archiving, not speed
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Practice Questions for Secondary Storage
Which of the following is a characteristic of secondary storage?
Describe how data is stored on a magnetic hard disk drive (HDD).
Quick Recall Flashcards
15 questions on Secondary Storage — practise free
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