RAID 5 Storage Calculator

When planning data storage solutions, understanding exactly how much usable space you get out of your RAID configuration is essential—especially when using RAID 5. That’s why we’ve created this simple, efficient RAID 5 Calculator to help you quickly determine the usable storage, parity storage, and total raw storage based on the number of disks and their size.

This guide will walk you through how the tool works, how to use it, and the practical implications of the results. Whether you’re setting up a home server, upgrading enterprise storage, or just curious about RAID 5, this tool and article will provide the clarity you need.

🔧 What Is the RAID 5 Calculator?

The RAID 5 Storage Calculator is a free online tool that allows users to input the number of hard drives (minimum of 3) and the size of each drive in gigabytes (GB). Based on these inputs, the calculator instantly displays:

  • Usable Storage: Total storage available for data after parity is considered.
  • Parity Storage: The space used to store parity information (used for data recovery).
  • Total Raw Storage: The full storage capacity of the array (all disks combined).

RAID 5 (Redundant Array of Independent Disks, level 5) uses striping with distributed parity, meaning it stripes data across all drives but reserves space for parity, enabling recovery if one drive fails. Understanding the trade-offs in storage capacity is critical for optimizing your setup.

🧭 How to Use the RAID 5 Calculator (Step-by-Step)

  1. Enter the Number of Disks
    • Input the number of hard drives you’re planning to use (minimum of 3).
    • For example, enter 4 if you have four drives.
  2. Enter Disk Size (GB)
    • Enter the capacity of each disk in gigabytes (GB).
    • For instance, if you’re using 1 TB drives, enter 1000.
  3. Click “Calculate”
    • The tool will instantly calculate and display the following:
      • Usable Storage
      • Parity Storage
      • Total Raw Storage
  4. Click “Reset” to Start Over
    • Want to try a new configuration? Hit “Reset” to clear the form.

🧮 Example: Calculating RAID 5 Storage

Let’s say you have 4 hard drives, each with 1000 GB of space.

Input:

  • Number of Disks: 4
  • Disk Size: 1000 GB

Calculation:

  • Total Raw Storage: 4 × 1000 = 4000 GB
  • Usable Storage: (4 – 1) × 1000 = 3000 GB
  • Parity Storage: 1 × 1000 = 1000 GB

Result:
You get 3000 GB of usable space, while 1000 GB is used for parity, ensuring data redundancy in case one drive fails.

🔍 Why Use RAID 5?

RAID 5 is one of the most popular RAID configurations due to its balance of performance, redundancy, and efficient storage use.

Key Benefits:

  • Redundancy: Can survive the failure of a single disk.
  • Cost-Efficient: Offers more usable space than RAID 1 or RAID 10.
  • Performance: Faster read speeds compared to single disks due to striping.

Best For:

  • File servers
  • Backup storage
  • Media libraries
  • Business servers requiring fault tolerance without excessive cost

💡 Additional Tips for RAID 5 Storage Planning

  • All drives should ideally be the same size and speed.
    Mixing disk sizes can cause you to lose usable space due to RAID defaulting to the smallest drive size.
  • RAID is not a backup.
    While RAID 5 offers fault tolerance, it should not replace regular backups. A failed rebuild or multiple drive failures can still result in data loss.
  • Watch out for UREs (Unrecoverable Read Errors)
    When rebuilding large arrays, the risk of UREs increases. Enterprise-grade drives are recommended for mission-critical data.
  • Performance hits during rebuilds
    If a drive fails, rebuilds can stress your system and significantly reduce performance.

❓ Frequently Asked Questions (FAQs)

1. What is RAID 5?

RAID 5 is a storage setup that uses striping with distributed parity to provide data redundancy and improved read speeds.

2. Why does RAID 5 require at least 3 disks?

Because RAID 5 needs to store both data and parity across multiple drives, at least three disks are required for it to function properly.

3. How is usable storage calculated in RAID 5?

Usable storage = (Number of disks – 1) × Disk size.

4. What is parity in RAID 5?

Parity is redundant data stored to allow reconstruction of information if a disk fails.

5. Can RAID 5 survive multiple disk failures?

No. RAID 5 can only survive one disk failure. If two drives fail, data is lost.

6. Is RAID 5 suitable for SSDs?

RAID 5 can be used with SSDs, but performance and endurance characteristics should be carefully evaluated.

7. What happens when a disk fails in RAID 5?

The system enters a degraded state but remains operational. Data is reconstructed from parity until the failed drive is replaced.

8. How long does it take to rebuild a RAID 5 array?

It depends on the size and speed of your disks, but it can take several hours or even days for large arrays.

9. Can I expand my RAID 5 array later?

Some RAID controllers support expansion, but it’s safer to plan your array size in advance.

10. Does RAID 5 protect against data corruption?

No. RAID 5 protects against disk failure, not against file corruption or accidental deletion.

11. Can I use RAID 5 on my NAS?

Yes, most NAS devices support RAID 5 for cost-effective, redundant storage.

12. What’s the difference between RAID 5 and RAID 6?

RAID 6 uses two parity blocks and can survive two disk failures, but at the cost of more storage overhead.

13. Is RAID 5 good for gaming or video editing?

RAID 5 can offer fast read speeds, but write speeds and fault recovery time may be a concern for real-time workloads.

14. Does RAID 5 require a hardware RAID controller?

No, software RAID (e.g., Windows Storage Spaces, mdadm on Linux) can implement RAID 5, but hardware RAID offers better performance.

15. Can I convert an existing RAID 0 or 1 to RAID 5?

Not directly. You’ll likely need to back up your data, reconfigure the array, and restore the data.

16. Is RAID 5 efficient for large storage arrays?

Up to a point. For large arrays (more than 6–8 disks), RAID 6 or other solutions may offer better fault tolerance.

17. What if my disk sizes are mismatched?

RAID 5 will treat all disks as the size of the smallest one, wasting any additional space on larger drives.

18. How often should I check the health of my RAID 5 array?

You should monitor the array status regularly and set up alerts for disk failures or degradation.

19. Is RAID 5 supported by all operating systems?

Most modern operating systems support RAID 5, either natively or via third-party software.

20. Does RAID 5 improve performance?

It can improve read performance due to striping, but write performance may suffer because of parity calculations.

🎯 Final Thoughts

Whether you’re building a server, setting up a NAS, or just exploring storage solutions, our RAID 5 Calculator is the perfect starting point. It helps you visualize how much storage you’ll truly get and whether RAID 5 fits your needs. Use it freely as you plan your next project, and make sure you’re getting the most out of every disk in your array.

Ready to test your configuration? Scroll up and use the RAID 5 Calculator now!