GCSEPaper 1Memory and storageSecondary storage
1.2.2

Secondary storage

Optical, magnetic and solid state storage and choosing storage for a scenario.

Learning Objectives

  • 1Explain why computers need secondary storage
  • 2Describe magnetic, optical and solid state storage
  • 3Compare storage devices using capacity, speed, portability, durability, reliability and cost
  • 4Recommend a suitable storage device or medium for a given scenario, with reasons

Why computers need secondary storage

Primary storage (RAM) is volatile, so anything in it is lost when the power is turned off. If a computer only had RAM, all your files, photos and programs would disappear every time you switched it off. Secondary storage solves this: it keeps data permanently, even without power, so files are still there next time you turn the computer on. It also has far more capacity than RAM.
Computers need secondary storage because primary storage (RAM) is volatile and has limited capacity. Secondary storage is non-volatile, so data, programs and the operating system can be stored permanently and are still available after the power is turned off. It also provides much greater capacity than RAM, which is needed to hold the operating system, applications and user files long-term.
Secondary storage is required because primary storage is volatile and comparatively small in capacity. Secondary storage provides non-volatile, permanent storage for the operating system, software and user files, with far greater capacity than RAM, allowing data to persist between sessions.

Think of it like...

RAM is your desk, cleared at the end of the day. Secondary storage is the filing cabinet that keeps everything safe overnight, ready for tomorrow.

Magnetic storage

Magnetic storage (e.g. a hard disk drive, HDD) stores data by magnetising parts of a spinning disk. It has large capacity for a low cost, so it is good value for storing lots of data. Because it has moving parts, it is slower than solid state storage and can be damaged if it is dropped or knocked while running. Another type of magnetic storage is magnetic tape, which is cheap and holds a huge amount of data, so it is mainly used for backups and archiving.
Magnetic storage (e.g. hard disk drives) uses moving parts to read and write data, which makes it slower than solid state storage and more vulnerable to damage from movement or impact. Its main advantage is that it offers large capacity at a relatively low cost per gigabyte, which is why it is often used for bulk or backup storage. Magnetic tape is a second example of magnetic storage: it has a very high capacity at low cost but only allows slow, sequential access, so it is used chiefly for backups and long-term archiving rather than everyday use.
Magnetic storage devices, such as HDDs, contain moving mechanical parts, giving them slower access speeds and lower durability than solid state storage, particularly if moved while in use. Their key advantage is a low cost per gigabyte at high capacity, making them well suited to large-scale or backup storage where speed and portability are less critical.

Optical storage

Optical storage (e.g. CDs, DVDs, Blu-ray discs) stores data that is read using a laser. It is cheap and portable, and discs are easy to distribute or share. However, optical discs have lower capacity than magnetic or solid state storage, and they can be scratched or damaged fairly easily.
Optical storage (CD, DVD, Blu-ray) is read using a laser. It is low cost and highly portable, making discs easy to distribute, but it has lower capacity than magnetic or solid state storage and is relatively easy to scratch or damage, which reduces reliability over time.
Optical storage is read via laser and offers low cost and strong portability, useful for distributing software or media. However, it has comparatively limited capacity and lower durability, as discs are prone to scratching, which can affect reliability.

Solid state storage

Solid state storage (e.g. SSDs, USB flash drives, SD cards) has no moving parts. This makes it faster than magnetic storage and much more durable, especially if the device is moved around. Its main downside is that it usually costs more per gigabyte than magnetic storage.
Solid state storage (SSDs, USB drives) has no moving parts, which gives it faster access speeds and greater durability than magnetic storage, particularly useful in portable devices that may be knocked or moved. The trade-off is a higher cost per gigabyte than magnetic storage of the same capacity.
Solid state storage has no moving mechanical parts, giving it faster access speeds and greater durability than magnetic storage, especially where a device may be in motion. It is generally more expensive per gigabyte than magnetic storage. Note: solid state storage is durable, not indestructible; it does not have an unlimited lifespan.
Magnetic (e.g. HDD)Large capacity, low costSlower, moving partsOptical (CD/DVD/Blu-ray)Cheap, portableLower capacity, scratches easilySolid state (SSD/USB)No moving parts: fast, durableHigher cost per GB

Choosing storage for a scenario

Exam questions often ask you to recommend a storage device for a scenario and justify your answer. Think about: capacity (how much data?), speed (how fast must it be accessed?), portability (does it need to be carried around?), durability (will it be dropped or knocked?), reliability (how important is it that data isn't lost?) and cost (what is the budget?).
To recommend storage for a scenario, weigh it against these characteristics: capacity, speed, portability, durability, reliability and cost. For example, a field reporter's camera needs durable, portable solid state storage since it will be carried and moved; a home media server storing large video libraries may prioritise capacity and cost, favouring magnetic storage instead.
Applying knowledge to a scenario means identifying which of capacity, speed, portability, durability, reliability and cost matter most for that context, then justifying a device choice against them. Full marks usually require a device recommendation plus a reason tied to a specific characteristic, not just naming the device.

Exam Phrasing: Use These Exact Phrases

  • ✓Secondary storage is non-volatile, so data is kept when the power is off
  • ✓Magnetic storage has large capacity at low cost, but is slower and has moving parts
  • ✓Optical storage is cheap and portable, but has lower capacity and can be scratched
  • ✓Solid state storage has no moving parts, so it is fast and durable, but costs more per GB
  • ✓Capacity, speed, portability, durability, reliability and cost
  • 💡For "recommend a device" questions, always give the device and a reason linked to one of the six characteristics, not just the device name.
  • 💡If a device will be carried around or could be knocked, that points to solid state (durability, no moving parts).
  • 💡Read whether the question wants a device or a type. Asked for a device, "magnetic" scores nothing, name a hard drive, SSD, USB stick or DVD. Asked for a type, name magnetic, optical or solid state.
  • 💡If the priority is lots of storage for little money, that points to magnetic storage (capacity and cost).
  • 💡Don't assume solid state lasts forever: it is more durable against impact, but it does not have an unlimited lifespan.

Wrong:

Solid state storage never wears out

Right:

Solid state storage is more durable against being dropped or moved, but it does not have an unlimited lifespan

Why it matters: OCR examiners specifically flagged this as a common misconception in real exam answers.

Wrong:

Secondary storage is used when the primary storage is full, or is only there for backups

Right:

Secondary storage permanently holds the operating system, software and files whether or not RAM is full; using storage as extra memory when RAM is full is virtual memory, which is a different idea

Why it matters: OCR examiners flagged both halves of this as a common misconception. Secondary storage is where data lives permanently, not an overflow for RAM and not just a backup.

Wrong:

Just naming a storage device answers a "recommend and justify" question

Right:

A full answer names the device AND explains why, linked to a characteristic like speed, durability or cost

Why it matters: Marks are usually awarded for the justification, not just the device name.

Wrong:

Magnetic storage is always the wrong choice because it is slower

Right:

Magnetic storage is still a good choice when capacity and low cost matter more than speed

Why it matters: Being slower does not make a device unsuitable; it depends what the scenario actually needs.

Question:

A musician records audio on location and needs to move around frequently while recording. State whether magnetic or solid state storage would be more suitable, and justify your answer. [2]

💡 Attempt this before revealing the answer, practice makes perfect!

Model Answer:

Solid state storage would be more suitable. This is because it has no moving parts, so it is more durable and less likely to be damaged if the musician moves around or knocks the device while recording.

Mark Scheme:

  • 1Identifies solid state storage
  • 2Justifies with durability / no moving parts, linked to the device being moved

Tap a card to flip it. Use the arrow keys to move and space to flip.

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Exam-style questions. Have a go, then reveal the mark scheme to check your answer.

1.State one reason why computers need secondary storage.

[1]

2.Identify two examples of magnetic secondary storage.

[2]

3.A school wants to back up 10 years of student records cheaply and does not need fast access. Recommend a type of secondary storage and justify your answer.

[2]

4.Explain why solid state storage is generally more durable than magnetic storage.

[2]

5.A photographer needs to carry a memory card in the field and wants their photos to be safe if the card is dropped. Recommend a type of storage and justify your answer, referring to at least two characteristics.

[3]

6.A school is buying laptops that students will carry between lessons every day. Discuss whether the laptops should use a hard disk drive or a solid state drive.

[8]

Extended response · marked in levels, not by counting points

2025Question paperMark schemeExaminers' report
2024Question paperMark schemeExaminers' report
2023Question paperMark schemeExaminers' report
2022Question paperMark schemeExaminers' report

The examiners' reports are the most useful and least read of the three: they say what candidates actually got wrong each year. All files are hosted by OCR.

Past-paper questions grouped by topic

The same OCR questions, sorted by topic rather than by year (via Physics & Maths Tutor).

2024
Paper 1

When justifying a choice between magnetic and solid state storage, strong answers linked solid state to faster access speed and durability if the device is moved, and linked magnetic to sufficient speed with a lower cost for high capacity. Weaker answers just said one was "faster" or "better" without saying faster/better at what.

Paper 1

Examiners noted a misconception that solid state storage has an unlimited lifespan and will always outlast magnetic storage. This is not correct: solid state is more durable against physical movement, but does not last forever.

Paper 1

Some candidates struggled to name a different type of secondary storage when asked, often repeating magnetic or solid state instead of giving optical. Make sure you can name all three types: magnetic, optical and solid state.

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