When building or upgrading a storage system, understanding the effective usable space of your RAID (Redundant Array of Independent Disks) setup is crucial. Different RAID levels offer varying balances between speed, redundancy, and capacity. To simplify this process, our RAID Drive Calculator lets you quickly estimate how much usable storage you’ll get from your chosen RAID configuration based on the number of drives and their sizes.
Raid Drive Calculator
What is the RAID Drive Calculator?
The RAID Drive Calculator is a user-friendly online tool designed to calculate the total usable storage available in a RAID array. It takes into account:
- The number of drives in the array
- The size of each individual drive (in terabytes)
- The RAID level selected
By entering these parameters, the calculator outputs the effective storage capacity you can expect after accounting for parity, mirroring, or striping overheads, depending on the RAID type.
How to Use the RAID Drive Calculator: Step-by-Step Guide
Using the RAID Drive Calculator is straightforward. Follow these simple steps:
1. Enter the Number of Drives
Specify how many hard drives or SSDs you will use in your RAID array. The calculator supports between 1 and 20 drives.
2. Enter the Size of Each Drive
Input the size (in terabytes, TB) of each individual drive. This can be fractional (e.g., 0.5 TB for 500GB drives) to fit your hardware setup.
3. Select the RAID Level
Choose your desired RAID level from the dropdown. The calculator supports common RAID levels including:
- RAID 0 (striping, no redundancy)
- RAID 1 (mirroring)
- RAID 5 (striping with single parity)
- RAID 6 (striping with double parity)
- RAID 10 (mirroring + striping)
4. Click Calculate
Press the Calculate button to see your usable storage capacity. The result appears below the inputs, showing how much effective storage space is available after RAID overhead.
5. Reset if Needed
Click the Reset button to clear inputs and start a new calculation.
Practical Examples
Example 1: RAID 5 with 5 Drives, Each 4TB
- Number of drives: 5
- Drive size: 4 TB
- RAID Level: RAID 5
Calculation:
Usable storage = (5 - 1) * 4 TB = 16 TB
This means you get 16TB of usable space with one drive reserved for parity, providing fault tolerance.
Example 2: RAID 10 with 6 Drives, Each 2TB
- Number of drives: 6
- Drive size: 2 TB
- RAID Level: RAID 10
Calculation:
Usable storage = (6 / 2) * 2 TB = 6 TB
RAID 10 offers both redundancy and performance by combining mirroring and striping, but you only get half of your total raw capacity.
Why Use This RAID Calculator?
- Time-saving: Instantly get usable storage without manual math.
- Accuracy: Avoid common RAID calculation errors.
- Planning: Helps in budgeting storage purchases and understanding capacity limits.
- Educational: Learn how different RAID levels affect storage and redundancy.
Understanding RAID Levels and Their Usable Storage
RAID 0: Striping Only
- Pros: Maximum storage and speed.
- Cons: No redundancy; if one drive fails, all data is lost.
- Usable storage: Total size of all drives combined.
RAID 1: Mirroring
- Pros: High redundancy by duplicating data.
- Cons: Usable storage equals one drive’s capacity.
- Usable storage: Size of a single drive.
RAID 5: Single Parity
- Pros: Good balance of storage efficiency and redundancy.
- Cons: Requires at least 3 drives.
- Usable storage: Total drives minus one, multiplied by drive size.
RAID 6: Double Parity
- Pros: Can tolerate two simultaneous drive failures.
- Cons: Requires minimum 4 drives; overhead of two drives.
- Usable storage: Total drives minus two, multiplied by drive size.
RAID 10: Mirroring + Striping
- Pros: Excellent performance and redundancy.
- Cons: Needs even number of drives (minimum 4); usable storage is half.
- Usable storage: Half the total raw capacity.
Additional Tips and Use Cases
- Use this calculator when designing NAS (Network Attached Storage) or SAN (Storage Area Network) solutions.
- Consider your priority: maximum capacity vs. data protection vs. speed.
- RAID is not a backup! Always maintain backups separately.
- RAID levels impact rebuild times — higher redundancy means longer rebuilds.
- Larger drives increase risk of failure during rebuild — plan accordingly.
Frequently Asked Questions (FAQs)
1. Can I use this calculator for SSD arrays?
Yes, it works the same way regardless of drive type.
2. Why does RAID 1 only show the capacity of one drive?
RAID 1 mirrors data, so usable capacity equals a single drive’s size.
3. Why does RAID 5 require at least 3 drives?
Because one drive is used for parity to protect data; fewer than 3 can't provide redundancy.
4. What happens if a drive fails in RAID 0?
All data is lost since RAID 0 has no redundancy.
5. Can I mix different-sized drives in RAID?
Technically yes, but the usable size per drive is limited to the smallest drive’s capacity.
6. How does RAID 6 differ from RAID 5?
RAID 6 uses two parity drives, allowing two drives to fail without data loss.
7. Is RAID 10 better than RAID 5?
RAID 10 offers better performance and faster rebuilds but requires more drives and halves usable capacity.
8. Does this calculator consider RAID controller overhead?
No, it calculates theoretical usable capacity based on drives and RAID type only.
9. Can I calculate RAID 50 or RAID 60 here?
No, currently only common RAID levels 0, 1, 5, 6, and 10 are supported.
10. What does “usable storage” mean?
It’s the actual storage available for data after RAID overhead is accounted for.
11. Why do RAID 5 and 6 subtract 1 or 2 drives?
Those drives store parity info used to rebuild data if one or two drives fail.
12. Can I use this calculator for enterprise storage planning?
Yes, it’s a quick estimation tool, but large deployments may require more detailed modeling.
13. How often should I back up RAID arrays?
Regularly—RAID protects against drive failure but not accidental deletion or corruption.
14. What is the minimum number of drives for RAID 10?
At least 4 drives, and the number must be even.
15. Can RAID improve read/write speeds?
Yes, especially RAID 0 and RAID 10 can significantly boost performance.
16. What if I enter invalid values?
The calculator alerts you to correct inputs like drive count or size.
17. Can I use drives with different capacities?
It’s not recommended; the smallest drive size typically defines usable space per drive.
18. Does RAID replace backup solutions?
No, RAID is for redundancy and availability, not backup.
19. Can I change RAID levels after setup?
Changing RAID levels usually requires reformatting or rebuilding arrays, losing data unless backed up.
20. What if my drives aren’t all the same size?
The usable capacity will be constrained by the smallest drive’s size in the array.
The RAID Drive Calculator empowers you to plan your storage efficiently, avoid costly mistakes, and choose the RAID setup that best fits your needs. Whether for home labs or enterprise-grade environments, this tool makes RAID capacity planning accessible and accurate. Try it today and take control of your storage infrastructure!