This key facts covers Quick Reference - Secondary Storage within Secondary Storage for GCSE Computer Science. Revise Secondary Storage in 3.4 Computer Systems for GCSE Computer Science with 17 exam-style questions and 18 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 10 of 11 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Quick Reference - Secondary Storage
Speed Ranking (Fastest to Slowest):
- SSD: 500-7000 MB/s (NVMe can reach 7 GB/s!)
- HDD: 100-200 MB/s
- Optical: 1-8 MB/s (50-200x slower than HDD)
Cost Ranking (Cheapest to Most Expensive per GB):
- HDD: £0.02-0.03 per GB
- Optical: ~£0.01 per GB (but very low total capacity)
- SSD: £0.10-0.15 per GB
Capacity Ranking (Highest to Lowest):
- HDD: 1-20 TB (consumer), up to 100TB+ (enterprise)
- SSD: 256 GB - 8 TB (consumer)
- Optical: 700 MB (CD) to 100 GB (Blu-ray triple-layer)
One-Sentence Summary:
- HDD: Cheap and huge but slow and fragile
- SSD: Fast and durable but expensive
- Optical: Portable and cheap per disc but very slow and low capacity
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).