---
title: RAID
description: Understand RAID concepts — hardware vs software, RAID levels, and how to set up redundant disk arrays for your homelab.
---


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# RAID

_Redundant Array of Independent Disks_

In computing, RAID (Redundant Array of Independent Disks) is a system that allows multiple hard drives to be combined to improve performance and/or reliability. It works by restructuring and distributing data blocks across the drives.

Originally, RAID systems were hardware-based, meaning a dedicated controller (a specific chip) managed data distribution and RAID operations. Today, most RAID systems (or their equivalents) are software-based. In fact, many software technologies can create RAID-like systems with features not available in hardware RAID, such as automatic repair (data scrubbing), snapshots, and more.

## Different Types of RAID

There are several types of RAID, each offering its own pros and cons. In general, RAID impacts the following five factors:

- Number of drives
- Total storage capacity
- Read speed
- Write speed
- Fault tolerance (resistance to hardware failure)

::warning

RAID is not a backup system but a service continuity system! It only allows hot-swapping of drives without interrupting your server or restoring from backup. You still need an external backup system.
::

### No RAID
---

<div style="display: flex; align-items: center;">
  <img src="/img/global/no-raid.svg" alt="Image" style="max-width: 30%; max-height:230px; margin-right: 20px;">
  <ul>
    <li>Just your disks, without RAID. Data is stored disk by disk.</li>
    <li>If you lose a disk, only its data is lost.</li>
    <li>Total capacity is the sum of all disks.</li>
  </ul>
</div>

Use your disks without RAID when you're not afraid of data loss and can tolerate service interruptions between failure and backup restoration.

### RAID 0
---

<div style="display: flex; align-items: center;">
  <img src="/img/global/raid0.svg" alt="Image" style="max-width: 30%; max-height:230px; margin-right: 20px;">
  <ul>
    <li>OS sees 1 drive.</li>
    <li>Data is striped across all disks.</li>
    <li>If you lose one disk, you lose all data.</li>
    <li>High read and write performance (multiplied by number of disks).</li>
    <li>Total capacity is the sum of all disks.</li>
    <li>Minimum of 2 disks required.</li>
  </ul>
</div>

Use RAID 0 when you prioritize performance and are not concerned about data loss. Ideal for temporary, high-speed storage (video editing, AI workloads, etc). Not suitable for long-term storage, as one failure means total data loss.

### RAID 1
---

<div style="display: flex; align-items: center;">
  <img src="/img/global/raid1.svg" alt="Image" style="max-width: 30%; max-height:230px; margin-right: 20px;">
  <ul>
    <li>OS sees 1 drive.</li>
    <li>All disks contain identical data.</li>
    <li>You can lose all but one disk.</li>
    <li>Improved read speed (scales with number of disks).</li>
    <li>Total capacity is equal to one disk (e.g., 2×10TB = 10TB).</li>
    <li>Minimum of 2 disks required.</li>
  </ul>
</div>

Use RAID 1 for strong redundancy. Each disk contains all data, so performance remains unaffected during a failure. Once failed disks are replaced, data is quickly restored. However, usable storage is limited to one disk’s capacity, making it an expensive solution.

::tip
✨ __Tip:__ You can combine RAID 1 with other RAID types to create mirrored arrays.
::

### RAID 5
---
<p align="center">
  <img src="/img/global/raid5.svg" alt="Image" style="max-width: 40%; margin-right: 20px;">
</p>

- OS sees 1 drive.
- Data is striped with parity blocks for redundancy.
- You can lose 1 disk and recover data.
- Improved read speed (scales with number of disks).
- Total capacity is the sum of all disks minus one (e.g., 3×10TB = 20TB).
- Minimum of 3 disks (4 recommended to reduce capacity loss).

Use RAID 5 when you want reliable storage with 3 to 5 disks and minimal space loss. It tolerates one disk failure but may have degraded performance during recovery, which can take days.

### RAID 6
---
<p align="center">
  <img src="/img/global/raid6.svg" alt="Image" style="max-width: 50%; margin-right: 20px;">
</p>

- OS sees 1 drive.
- Data is striped with dual parity blocks.
- You can lose 2 disks and still recover data.
- Improved read speed (scales with number of disks).
- Total capacity is the sum of all disks minus two (e.g., 4×10TB = 20TB).
- Minimum of 4 disks (6 recommended to minimize space loss).

Use RAID 6 in similar situations as RAID 5, especially with 6 or more disks. More disks mean higher failure risk. RAID 6 offers peace of mind by tolerating two simultaneous failures.

## Software RAID
(coming soon)
