To compare storage types, pick the requirement first, then judge each device against it on capacity, speed, portability, durability and cost. A comparison needs both sides: say what one device does and what the other does differently.
This lesson sits in the hardware, software and systems module and builds on choosing devices from a scenario in lesson one.
What are the main storage types?
- Magnetic (hard disk drive): large capacity for the price, has moving parts, so it is more easily damaged by knocks.
- Solid state (SSD and flash): no moving parts, fast to read and write, tough and quiet, but usually costs more per unit of capacity.
- Optical (CD, DVD, Blu-ray): cheap discs, easy to post, but a small capacity and slower access, and they scratch.
- Portable flash (USB stick, memory card): very small, easy to carry, convenient for moving files, but easy to lose.
Exact capacities change over time, so treat any figures in this lesson as made-up classroom numbers and check your course notes for the sizes your syllabus expects.
How do you compare in a scenario?
- Write the requirement as a short list: how much data, how fast, carried or fixed, how long it must last.
- Test each device against each point.
- Choose the one that meets most points, and say which point decided it.
- Write a two-sided sentence: “X is better than Y for this client because…”
Worked example
A wedding photographer takes 120 photos at about 5 MB each at every event. She wants to hand the client the photos on a disc and also keep a tough drive in her bag. Does one event fit on a 4.7 GB DVD?
Step 1, size of one event: 120 × 5 MB = 600 MB.
Step 2, convert the disc: 4.7 GB = 4 700 MB, using 1 GB = 1 000 MB for this sum.
Step 3, compare: 600 MB is well below 4 700 MB, so one event fits on one DVD.
Step 4, how many events fit? 4 700 ÷ 600 = 7.83…, so seven whole events fit, with room left over.
Step 5, choose for the bag: a flash-based portable drive, because it has no moving parts, so it survives knocks better than a magnetic drive, and it is small enough to carry.
Check by multiplying back: 7 × 600 = 4 200 MB, which is under 4 700 MB, and 8 × 600 = 4 800 MB, which is over. Seven is correct.
What mistake do students make?
The usual slip is to compare with a single word.
Mistaken answer: “A hard disk is better because it is bigger.”
This gives no second device and no link to the client’s need.
The correction is a two-sided sentence tied to the need: “A hard disk gives more capacity than a memory card, which suits a photographer storing thousands of photos. But a memory card is lighter and easier to carry.”
Check yourself
1. A student wants to carry one small presentation file between school and home. Name a suitable storage type and give one reason.
Show answer
A USB flash drive. It is small and easy to carry, and it holds far more than the file needs.
2. A school wants to keep years of student records in one place and does not need to move them. Which type suits better, magnetic or portable flash, and why?
Show answer
Magnetic hard disk storage. It offers large capacity for the price and does not need to be portable.
3. A film club has 25 GB of video to burn onto 4.7 GB discs. How many discs are needed?
Show answer
25 ÷ 4.7 = 5.31…, so you must round up to 6 discs. Five discs would hold only 23.5 GB.
Where does this lead next?
Continue to explaining an input-output pathway, which shows where storage fits in a whole system. The mixed practice set includes more capacity sums.
Students who enjoy the sums often lose marks on comparison wording, which is a good thing to rehearse in online one-to-one ICT tuition.