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Worked Example: Comparing Storage Types

Explore each storage type in detail and understand when to use each one.

Deep Dive: Understanding Each Storage Type

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Magnetic Storage

How Hard Disk Drives Work

Spinning Platters
↻ 5400-7200 RPM
Read/Write Head
Hovers nanometers above surface
1

Platters spin at high speed

2

Arm moves to correct position

3

Head reads/writes magnetic patterns

Characteristics Explained

💾 Capacity
★★★★★ Excellent

Up to 20TB+ per drive. Best for bulk storage.

A 4TB HDD costs ~£70 and holds 1 million photos!
⚡ Speed
★★★☆☆ Medium

80-200 MB/s sequential. Slow random access due to physical movement.

Loading a game: 30-60 seconds
💪 Durability
★★☆☆☆ Low

Moving parts are vulnerable. A drop can cause "head crash" and data loss.

Never move an HDD while it's running!
💰 Cost
★★★★★ Cheapest

~£15-20 per TB. Best value for large storage needs.

1TB HDD: £35 vs 1TB SSD: £60-80

Best Used For:

  • 📸 Storing large photo/video libraries
  • 🗄️ File servers and NAS devices
  • 💾 Desktop computer secondary storage
  • 📼 Backup drives (external HDDs)
⚡

Solid State Storage

How SSDs Work

NAND Flash Chips
Controller
Manages data across chips
1

Data stored as electrical charges

2

No moving parts - purely electronic

3

Instant access to any location

Characteristics Explained

⚡ Speed
★★★★★ Excellent

SATA SSD: 500 MB/s. NVMe SSD: 3000-7000 MB/s!

Loading a game: 5-15 seconds
💪 Durability
★★★★★ Excellent

No moving parts. Survives drops, shocks, vibration.

Safe in laptops, tablets, phones
💾 Capacity
★★★★☆ Good

Up to 8TB available, but expensive at high capacities.

Most common: 256GB - 2TB
💰 Cost
★★☆☆☆ Expensive

~£50-80 per TB. Prices dropping but still more than HDD.

Worth it for speed-critical tasks

Types of SSDs:

SATA SSD

~500 MB/s

Uses same connector as HDD

Good value upgrade from HDD

NVMe SSD

~3000-7000 MB/s

Connects directly to motherboard

Best performance available

Best Used For:

  • 💻 Operating system drive (boot drive)
  • 🎮 Games that need fast loading
  • 🎬 Video editing scratch disk
  • 📱 Smartphones and tablets
  • 🎒 Portable storage (USB flash drives)
💿

Optical Storage

How Optical Discs Work

Pits and Lands
Laser reads reflections
1

Laser shines on disc surface

2

Pits scatter light, lands reflect it

3

Pattern of reflections = data

Types of Optical Media:

CD

700 MB

Music, small files

DVD

4.7 GB (single) / 8.5 GB (dual)

Films, software

Blu-ray

25 GB (single) / 50 GB (dual)

HD video, games, archives

Characteristics Explained

💿 Capacity
★★☆☆☆ Low

700MB to 50GB max. Tiny compared to HDD/SSD.

One Blu-ray = one 4K movie
⚡ Speed
★☆☆☆☆ Slow

1-50 MB/s. Much slower than HDD or SSD.

Installing from DVD takes ages
📦 Portability
★★★★☆ Good

Thin and light. Easy to post or store.

Perfect for mailing software
💰 Cost
★★★★★ Very Cheap

Pennies per disc when mass-produced.

50 blank DVDs: £10

Best Used For:

  • 🎬 Film and music distribution
  • 🎮 Game console games (PlayStation, Xbox)
  • 📀 Software installation discs
  • 🗄️ Long-term archival (M-DISC lasts 1000 years!)

⚠️ Important Note:

Many modern laptops don't have optical drives! Always check compatibility before choosing optical media.

Decision Guide: Choosing Storage

What's most important?

SPEED
Choose SSD
CAPACITY + LOW COST
Choose HDD
MASS DISTRIBUTION
Choose Optical
LONG-TERM ARCHIVE
Choose Tape
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