Basic 8 · Computing · Storage Systems
Storage Systems and Capacity
In this topic you will describe magnetic, optical, solid-state and cloud storage systems, explain units of storage capacity, and choose suitable storage and backup methods.
By the end of these notes you should be able to:
- Describe magnetic, optical and solid-state storage
- Explain cloud storage and its advantages and disadvantages
- Explain units of storage capacity and choose suitable storage
What you already know
- Storage devices (Basic 7)
Copy everything that has a blue line on its left into your notebook. The other parts are for reading.
Lesson 1
- Strand
- Introduction To Computing
- Sub-strand
- Storage Systems
- Indicator
- B8.1.1.1.4 – Describe storage devices
Introduction
Your photos might be on your phone's memory card, your school notes on a flash drive and your email in the cloud. Each is a different kind of storage system.
1. Primary and Secondary Storage
Primary storage (RAM and ROM) is directly accessed by the CPU. RAM is fast but volatile: it loses data when power is off. Secondary storage keeps data permanently and is non-volatile. This lesson focuses on secondary storage systems.
2. Magnetic Storage
Magnetic storage records data by magnetising tiny areas on a surface. Hard disk drives (HDDs) have spinning platters and moving read/write heads. They offer large capacity at low cost but can be damaged by drops and magnets. Magnetic tape is used by large organisations to back up huge amounts of data cheaply.
3. Optical Storage
Optical storage uses a laser to read and write data as tiny pits on a disc. CDs hold about 700 MB, DVDs about 4.7 GB and Blu-ray discs 25 to 50 GB. Optical discs are cheap and portable, but they scratch easily, are slow and are now less common.
4. Solid-State Storage
Solid-state storage uses flash memory chips with no moving parts. Examples include solid-state drives (SSDs), USB flash drives, memory cards (SD and microSD) and the built-in storage of phones. They are fast, quiet, light and resistant to shock, but cost more per gigabyte than HDDs and can wear out after very many write cycles.
| Type | Examples | Advantages | Disadvantages |
|---|---|---|---|
| magnetic | HDD, magnetic tape | large capacity, cheap | moving parts, damaged by drops and magnets |
| optical | CD, DVD, Blu-ray | cheap, portable | small capacity, scratches, slow |
| solid-state | SSD, flash drive, memory card | fast, durable, silent | more expensive per GB |
| cloud | Google Drive, OneDrive, iCloud | access anywhere, automatic backup | needs internet, privacy concerns |
5. Cloud Storage
Cloud storage: Storing data on remote servers owned by a company and accessed through the internet.
Cloud storage lets you open files from any device with internet access and protects them if your phone is lost. However, it needs a reliable internet connection and data bundle, and you must trust the company with your information. Use strong passwords and two-step verification to protect cloud accounts.
New words
- volatile
- Losing data when power is switched off.
- magnetic storage
- Storage that records data by magnetising a surface.
- optical storage
- Storage read and written by laser.
- cloud storage
- Storage on remote servers accessed through the internet.
Summary
- Secondary storage is non-volatile and includes magnetic, optical, solid-state and cloud storage.
- Each type has advantages and disadvantages in capacity, speed, cost and durability.
- Cloud storage offers access anywhere but needs internet and careful security.
Class activity: Storage Comparison
- Examine a USB flash drive, a hard disk drive and a memory card.
- Classify each and list its advantages and disadvantages.
- Recommend storage for three different users.
You need: USB flash drive, Hard disk drive, Memory card
Exercises
Answer in your exercise book first, then check your answers.
1. Which storage uses a laser?
- A. optical
- B. magnetic
- C. solid-state
- D. RAM
Show answer
Answer: opticalCDs and DVDs.2. Which storage has no moving parts?
- A. SSD
- B. HDD
- C. magnetic tape
- D. DVD drive
Show answer
Answer: SSDFlash memory.3. RAM is volatile.
- A. True
- B. False
Show answer
Answer: TrueLoses data without power.4. Storing data on remote servers through the internet is ______ storage.
Show answer
Answer: cloudOnline.5. State two advantages and two disadvantages of cloud storage.
Show answer
Answer: Advantages: access anywhere, automatic backup. Disadvantages: needs internet, privacy risks.Two each.6. Recommend storage for a photographer who needs to carry many large files and explain.
Show answer
Answer: A portable SSD, because it is fast, durable and holds large files in a small device.Justified choice.
Lesson 2
- Strand
- Introduction To Computing
- Sub-strand
- Storage Systems
- Indicator
- B8.1.1.1.4 – Describe storage devices
Introduction
How many songs can a 16 GB memory card hold? To answer, we need to understand units of storage capacity.
1. Units of Storage
| Unit | Size | Roughly equal to |
|---|---|---|
| bit (b) | 0 or 1 | one on/off switch |
| byte (B) | 8 bits | one character, such as "A" |
| kilobyte (KB) | about 1,000 bytes (1,024) | a short paragraph of text |
| megabyte (MB) | about 1,000 KB | a photo or one minute of MP3 music |
| gigabyte (GB) | about 1,000 MB | a full-length film |
| terabyte (TB) | about 1,000 GB | hundreds of films or many thousands of photos |
In computing, each unit is strictly 1,024 times the one before, because computers work in powers of 2 (2¹⁰ = 1,024). Manufacturers often use 1,000 for simplicity, which is why a "500 GB" drive may show slightly less space on a computer.
2. Calculating Storage Needs
Calculate
A song is about 4 MB. How many songs can fit on a 16 GB memory card?
- 16 GB ≈ 16 × 1,000 MB = 16,000 MB.
- 16,000 ÷ 4 = 4,000.
Answer: About 4,000 songs
3. Choosing Suitable Storage
| User need | Suitable storage |
|---|---|
| carry school files between home and school | USB flash drive |
| store photos and videos on a phone | microSD card and cloud backup |
| fast computer start-up and programs | internal SSD |
| cheap storage for a large music and film library | external HDD |
| share files with classmates anywhere | cloud storage |
4. Backing Up Data
A backup is a copy of important data kept in a separate place. A common rule is the 3-2-1 rule: keep three copies of important files, on two different types of storage, with one copy in a different location, such as the cloud. Backing up protects your work from loss due to theft, damage, viruses or accidental deletion.
5. Storage Security
Stored data must be protected. Use passwords or PINs on phones and computers, encrypt sensitive files where possible, scan flash drives for viruses before opening files, and never leave storage devices with private information lying around. Losing an unprotected flash drive with school reports or personal photos can expose private information to strangers.
New words
- byte
- A group of 8 bits.
- gigabyte
- About one thousand megabytes.
- backup
- A copy of data kept for safety.
- 3-2-1 rule
- Three copies, two types of storage, one off-site.
Summary
- Storage is measured in bits, bytes, KB, MB, GB and TB, each about 1,000 (strictly 1,024) times the last.
- Calculate storage needs by dividing capacity by file size.
- Choose storage to suit the need and back up data using the 3-2-1 rule.
Class activity: Storage Calculations
- Find the size of a photo, a song and a video on a phone or computer.
- Calculate how many of each fit on 8 GB, 16 GB and 64 GB devices.
- Plan a 3-2-1 backup for your school files.
You need: USB flash drive, Hard disk drive, Memory card
Exercises
Answer in your exercise book first, then check your answers.
1. How many bits make a byte?
- A. 8
- B. 2
- C. 10
- D. 1,024
Show answer
Answer: 8Byte.2. Which is the largest unit?
- A. terabyte
- B. gigabyte
- C. megabyte
- D. kilobyte
Show answer
Answer: terabyteAbout 1,000 GB.3. A backup is a copy of data kept for safety.
- A. True
- B. False
Show answer
Answer: TrueProtection.4. About one thousand megabytes make one ______.
Show answer
Answer: gigabyteGB.5. How many 5 MB files can fit on a 2 GB flash drive?
Show answer
Answer: About 400 files (2,000 ÷ 5).Calculation.6. Explain the 3-2-1 backup rule.
Show answer
Answer: Keep three copies of important data on two different storage types, with one copy stored off-site or in the cloud.Backup strategy.
Homework
- Check the storage capacity and free space on a phone or computer at home and record them.