LearnViz CompSci
Home / Learn / Computer Architecture & Logic / RAID

Advanced Topic 45 of 51 Computer Architecture & Logic

RAID

Combining disks for redundancy or performance.

How it works

RAID combines multiple drives into one logical unit to improve performance, reliability or both. RAID 0 stripes data across drives for speed with no redundancy; RAID 1 mirrors for fault tolerance; RAID 5 stripes with distributed parity to survive one failure; RAID 6 uses double parity for two failures; RAID 10 combines mirroring and striping. Parity is computed with XOR so lost data can be rebuilt.

Step-by-step walkthrough

  1. RAID 0 stripes data across disks for speed, with no redundancy.
  2. RAID 1 mirrors data on two disks.
  3. RAID 5 stores data plus rotating parity.
  4. If one disk fails its content is rebuilt by XOR of the others.
  5. RAID is not a backup, it does not protect against deletion.

Where it is used

Servers, network-attached storage, databases and virtualization hosts use RAID for availability and throughput. Hardware controllers or software such as Linux md manage the arrays.

Common pitfall

RAID is not a backup: it does not protect against deletion, corruption or fire. Rebuilds on large drives take long and stress the surviving disks, and a second failure during rebuild loses data. RAID 5 has the write penalty for small writes. Match the level to the workload and monitor drive health.

Where it fits in the course

RAID is topic 45 of 51 in Computer Architecture & Logic, rated Advanced. It follows Storage Devices. The next topic is Memory Consistency Models.

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 RAID?
Combining disks for redundancy or performance. It belongs to Computer Architecture & Logic and is an advanced-level topic.
Where do people use RAID?
Servers, network-attached storage, databases and virtualization hosts use RAID for availability and throughput.
What is the most common mistake with RAID?
RAID is not a backup: it does not protect against deletion, corruption or fire.
What should I learn before this topic?
Start with Storage Devices, 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 RAID 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 RAID?
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 RAID?
Storage Devices, Memory Consistency Models, Bus Architecture are closely connected. The full list is in the related topics section of this page.
What should I study after RAID?
Continue with Memory Consistency Models, the next topic in Computer Architecture & Logic.

Related topics