HDD · SSD · Optical · Magnetic Tape · Choosing the Right Storage
CSZoneEdexcel GCSE Computer Science 1CP2
Types of Secondary Storage
Non-volatile, Persistent Storage
HDD (Hard Disk Drive): magnetic storage on spinning platters. Large capacity (TB), low cost per GB. Slow compared to SSD; has moving parts — fragile and noisy.
SSD (Solid State Drive): flash memory — no moving parts. Very fast, silent, durable. More expensive per GB than HDD.
Optical (CD/DVD/Blu-ray): laser reads/writes pits and lands. Good for distribution and backup. Low capacity, slow, easily scratched.
Magnetic Tape & Cloud
Specialist and Remote Storage
Magnetic tape: very large capacity, very cheap per GB, but very slow sequential access. Used for long-term archival backup — not for fast retrieval.
Cloud storage: data stored on remote servers and accessed over the internet. Accessible from anywhere; depends on internet connection; subscription cost; security risks.
Comparing Storage Types
Speed, Capacity, Cost, Durability
Speed: SSD > HDD > Optical > Tape
Capacity: Tape > HDD > SSD > Optical (generally)
Cost per GB: Tape/HDD cheapest; SSD more expensive; Optical variable
Durability: SSD most durable (no moving parts); HDD fragile; optical can scratch; tape can degrade
Exam tip: Match storage type to use case — e.g. laptop → SSD; archive → tape; software distribution → optical
Exam Practice
Have a go at this question
Edexcel-style question
A company wants to back up large amounts of data cheaply and does not need fast access. State the most appropriate storage type and give two reasons for your choice.
3 marks
Magnetic tape [1]. Very high capacity, suitable for large amounts of data [1]. Very low cost per GB for archival storage [1]. (Accept HDD with appropriate justification.)