Type 1: Magnetic Storage (HDD - Hard Disk Drive)
Part of Secondary Storage — GCSE Computer Science
This key facts covers Type 1: Magnetic Storage (HDD - Hard Disk Drive) 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 4 of 10 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 4 of 10
Practice
15 questions
Recall
18 flashcards
Type 1: Magnetic Storage (HDD - Hard Disk Drive)
How It Works:
Uses spinning metal platters (discs) coated with magnetic material. A read/write head floats nanometers above the platter surface, reading and writing data by magnetizing tiny regions. Like a high-tech record player that can also record!
Key Components:
- Platters: Metal discs that spin at 5,400-15,000 RPM (revolutions per minute)
- Read/write heads: Electromagnets that magnetize regions to store binary data
- Actuator arm: Moves heads across platter to different tracks
- Spindle motor: Spins the platters at constant speed
- Controller: Manages data transfer between HDD and computer
Advantages:
- Very cheap per GB - best value for large storage (£0.02-0.03 per GB)
- High capacity available - consumer HDDs go up to 20TB+
- Mature technology - reliable and well-understood
- No write cycle limit - can write indefinitely
- Good for bulk storage, backups, archives
Disadvantages:
- Slow compared to SSD (100-200 MB/s typical, 5-10ms access time)
- Has moving parts - fragile, can fail if dropped or shocked
- Mechanical noise (spinning, clicking, seeking sounds)
- Uses more power - generates heat, drains laptop battery faster
- Vulnerable to physical damage, head crashes, wear over time
Best Used For:
- Large file storage (video libraries, photo archives, backups)
- Desktop computers where weight/power don't matter
- Network-attached storage (NAS) for homes and small businesses
- Budget builds where cost per GB is priority