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Advanced Topic 44 of 51 Computer Architecture & Logic

Storage Devices

HDDs and SSDs and how they persist data.

How it works

Storage devices hold data persistently. Hard disk drives store bits magnetically on spinning platters read by moving heads, giving large capacity at low cost but millisecond seek times. Solid-state drives use NAND flash with no moving parts, achieving microsecond latency and high throughput, but cells wear out after limited write cycles and are managed by a controller with wear leveling. Interfaces include SATA, SAS and NVMe over PCIe.

Step-by-step walkthrough

  1. An HDD moves a head over a spinning platter, seeks take milliseconds.
  2. An SSD stores bits as charge in flash cells with no moving parts.
  3. Data is read in pages and erased in large blocks.
  4. The controller maps logical addresses to flash and wears evenly.
  5. Both connect to the host over SATA or NVMe.

Where it is used

Operating systems, databases, backups, media libraries and cloud object stores rely on storage. Tiering combines fast and slow devices by access pattern.

Common pitfall

Sequential access is far faster than random on hard disks. SSD write amplification and garbage collection cause performance variation and wear. Data in volatile memory is lost on power failure unless flushed, so durability requires fsync and awareness of drive caches. Plan for drive failures with backups and redundancy.

Where it fits in the course

Storage Devices is topic 44 of 51 in Computer Architecture & Logic, rated Advanced. It follows Bus Architecture. The next topic is RAID.

Practice and explore

How to study this topic

  1. Read the explanation above and restate the definition in your own words.
  2. Open the interactive lesson and answer its mini quiz.
  3. Read the common pitfall, then write a short example that avoids it.
  4. Check your understanding in the Computer Architecture & Logic quiz, and revisit the topic if you miss a question.

Frequently asked questions

What is Storage Devices?
HDDs and SSDs and how they persist data. It belongs to Computer Architecture & Logic and is an advanced-level topic.
Where do people use Storage Devices?
Operating systems, databases, backups, media libraries and cloud object stores rely on storage.
What is the most common mistake with Storage Devices?
Sequential access is far faster than random on hard disks.
What should I learn before this topic?
Start with Bus Architecture, the topic just before it in Computer Architecture & Logic.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the Computer Architecture & Logic quiz.
Is Storage Devices hard to learn?
It is an Advanced topic. Expect to read the explanation more than once and to connect it with earlier topics. Working through a small example by hand helps most.
How long does it take to learn Storage Devices?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to Storage Devices?
Bus Architecture, RAID, Interrupts are closely connected. The full list is in the related topics section of this page.
What should I study after Storage Devices?
Continue with RAID, the next topic in Computer Architecture & Logic.

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